UPC: Difference between revisions

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=={{header|Racket}}==
=={{header|Racket}}==


<lang racket></lang>
<lang racket>#lang racket

;; inspired by Kotlin

(define (is-#? c) (char=? c #\#))

(define left-digits
(for/hash ((i (in-naturals))
(c '((#f #f #t #t #f)
(#f #t #t #f #f)
(#f #t #f #f #t)
(#t #t #t #t #f)
(#t #f #f #f #t)
(#t #t #f #f #f)
(#t #f #t #t #t)
(#t #t #t #f #t)
(#t #t #f #t #t)
(#f #f #t #f #t))))
(values `(#f ,@c #t) i)))

(define right-digits (for/hash (([k v] left-digits)) (values (map not k) v)))

(define (lookup-blocks bits hsh fail)
(let recur ((bs bits) (r null))
(if (null? bs)
(reverse r)
(let-values (((bs′ tl) (split-at bs 7)))
(let ((d (hash-ref hsh bs′ (λ () (fail (list 'not-found bs′))))))
(recur tl (cons d r)))))))

(define (extract-blocks b fail)
(let*-values
(((e-l-m-r-e) (map is-#? (string->list (string-trim b))))
((_) (unless (= (length e-l-m-r-e) (+ 3 (* 7 6) 5 (* 7 6) 3))
(fail 'wrong-length)))
((e l-m-r-e) (split-at e-l-m-r-e 3))
((_) (unless (equal? e '(#t #f #t)) (fail 'left-sentinel)))
((l-m-r e) (split-at-right l-m-r-e 3))
((_) (unless (equal? e '(#t #f #t)) (fail 'right-sentinel)))
((l m-r) (split-at l-m-r 42))
((m r) (split-at m-r 5))
((_) (unless (equal? m '(#f #t #f #t #f)) (fail 'mid-sentinel))))
(values l r)))

(define (upc-checksum? ds)
(zero? (modulo (for/sum ((m (in-cycle '(3 1))) (d ds)) (* m d)) 10)))

(define (lookup-digits l r fail (transform values))
(let/ec fail-lookups
(define ds (append (lookup-blocks l left-digits (λ _ (fail-lookups #f)))
(lookup-blocks r right-digits (λ _ (fail-lookups #f)))))
(if (upc-checksum? ds)
(transform ds)
(fail (list 'checksum (transform ds))))))

(define (decode-upc barcode upside-down fail)
(define-values (l r) (extract-blocks barcode fail))
(or (lookup-digits l r fail)
(lookup-digits (reverse r) (reverse l) fail upside-down)))

(define (report-upc barcode)
(displayln (decode-upc barcode
(λ (v) (cons 'upside-down v))
(λ (e) (format "invalid: ~s" e)))))

(define (UPC)
(for-each report-upc
'(" # # # ## # ## # ## ### ## ### ## #### # # # ## ## # # ## ## ### # ## ## ### # # # "
" # # # ## ## # #### # # ## # ## # ## # # # ### # ### ## ## ### # # ### ### # # # "
" # # # # # ### # # # # # # # # # # ## # ## # ## # ## # # #### ### ## # # "
" # # ## ## ## ## # # # # ### # ## ## # # # ## ## # ### ## ## # # #### ## # # # "
" # # ### ## # ## ## ### ## # ## # # ## # # ### # ## ## # # ### # ## ## # # # "
" # # # # ## ## # # # # ## ## # # # # # #### # ## # #### #### # # ## # #### # # "
" # # # ## ## # # ## ## # ### ## ## # # # # # # # # ### # # ### # # # # # "
" # # # # ## ## # # ## ## ### # # # # # ### ## ## ### ## ### ### ## # ## ### ## # # "
" # # ### ## ## # # #### # ## # #### # #### # # # # # ### # # ### # # # ### # # # "
" # # # #### ## # #### # # ## ## ### #### # # # # ### # ### ### # # ### # # # ### # # "
; first element again, with corrupted second digit
" # # # ## # ## # ## ### ## ### ## #### # # # ## ## # # ## ## ### # ## ## ### # # # ")))

(module+ main (UPC))</lang>


{{out}}
{{out}}


<pre>(9 2 4 7 7 3 2 7 1 0 1 9)
<pre></pre>
(4 0 3 9 4 4 4 4 1 0 5 0)
(upside-down 8 3 4 9 9 9 6 7 6 7 0 6)
(upside-down 9 3 9 8 2 5 1 5 8 8 1 1)
#f
(upside-down 3 1 6 3 1 3 7 1 8 7 1 7)
(2 1 4 5 7 5 8 7 5 6 0 8)
(upside-down 8 1 8 7 7 8 8 4 1 8 1 3)
(7 0 6 4 6 6 7 4 3 0 3 0)
(6 5 3 4 8 3 5 4 0 4 3 5)
invalid: (checksum (9 9 4 7 7 3 2 7 1 0 1 9))</pre>


=={{header|Raku}}==
=={{header|Raku}}==

Revision as of 16:54, 31 August 2021

Task
UPC
You are encouraged to solve this task according to the task description, using any language you may know.
Goal

Convert UPC bar codes to decimal.


Specifically:

The UPC standard is actually a collection of standards -- physical standards, data format standards, product reference standards...

Here,   in this task,   we will focus on some of the data format standards,   with an imaginary physical+electrical implementation which converts physical UPC bar codes to ASCII   (with spaces and   #   characters representing the presence or absence of ink).


Sample input

Below, we have a representation of ten different UPC-A bar codes read by our imaginary bar code reader:

         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       
        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         
         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         
       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        
         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          
          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         
         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        
        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         
         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       
        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         

Some of these were entered upside down,   and one entry has a timing error.


Task

Implement code to find the corresponding decimal representation of each, rejecting the error.

Extra credit for handling the rows entered upside down   (the other option is to reject them).


Notes

Each digit is represented by 7 bits:

    0:  0 0 0 1 1 0 1
    1:  0 0 1 1 0 0 1
    2:  0 0 1 0 0 1 1
    3:  0 1 1 1 1 0 1
    4:  0 1 0 0 0 1 1
    5:  0 1 1 0 0 0 1
    6:  0 1 0 1 1 1 1
    7:  0 1 1 1 0 1 1
    8:  0 1 1 0 1 1 1
    9:  0 0 0 1 0 1 1

On the left hand side of the bar code a space represents a 0 and a # represents a 1.
On the right hand side of the bar code, a # represents a 0 and a space represents a 1
Alternatively (for the above):   spaces always represent zeros and # characters always represent ones, but the representation is logically negated -- 1s and 0s are flipped -- on the right hand side of the bar code.


The UPC-A bar code structure
  •   It begins with at least 9 spaces   (which our imaginary bar code reader unfortunately doesn't always reproduce properly),
  •   then has a     # #     sequence marking the start of the sequence,
  •   then has the six "left hand" digits,
  •   then has a   # #   sequence in the middle,
  •   then has the six "right hand digits",
  •   then has another   # #   (end sequence),   and finally,
  •   then ends with nine trailing spaces   (which might be eaten by wiki edits, and in any event, were not quite captured correctly by our imaginary bar code reader).


Finally, the last digit is a checksum digit which may be used to help detect errors.


Verification

Multiply each digit in the represented 12 digit sequence by the corresponding number in   (3,1,3,1,3,1,3,1,3,1,3,1)   and add the products.

The sum (mod 10) must be 0   (must have a zero as its last digit)   if the UPC number has been read correctly.

11l

Translation of: Kotlin

<lang 11l>V LEFT_DIGITS = [

  ‘   ## #’ = 0,
  ‘  ##  #’ = 1,
  ‘  #  ##’ = 2,
  ‘ #### #’ = 3,
  ‘ #   ##’ = 4,
  ‘ ##   #’ = 5,
  ‘ # ####’ = 6,
  ‘ ### ##’ = 7,
  ‘ ## ###’ = 8,
  ‘   # ##’ = 9

]

V RIGHT_DIGITS = Dict(LEFT_DIGITS.items(), (k, v) -> (k.replace(‘ ’, ‘s’).replace(‘#’, ‘ ’).replace(‘s’, ‘#’), v))

V END_SENTINEL = ‘# #’ V MID_SENTINEL = ‘ # # ’

F decodeUPC(input)

  F decode(candidate)
     V pos = 0
     V part = candidate[pos .+ :END_SENTINEL.len]
     I part == :END_SENTINEL
        pos += :END_SENTINEL.len
     E
        R (0B, [Int]())
     [Int] output
     L 6
        part = candidate[pos .+ 7]
        pos += 7
        I part C :LEFT_DIGITS
           output [+]= :LEFT_DIGITS[part]
        E
           R (0B, output)
     part = candidate[pos .+ :MID_SENTINEL.len]
     I part == :MID_SENTINEL
        pos += :MID_SENTINEL.len
     E
        R (0B, output)
     L 6
        part = candidate[pos .+ 7]
        pos += 7
        I part C :RIGHT_DIGITS
           output [+]= :RIGHT_DIGITS[part]
        E
           R (0B, output)
     part = candidate[pos .+ :END_SENTINEL.len]
     I part == :END_SENTINEL
        pos += :END_SENTINEL.len
     E
        R (0B, output)
     V sum = 0
     L(v) output
        I L.index % 2 == 0
           sum += 3 * v
        E
           sum += v
     R (sum % 10 == 0, output)
  V candidate = input.trim(‘ ’)
  V out = decode(candidate)
  I out[0]
     print(out[1])
  E
     out = decode(reversed(candidate))
     I out[0]
        print(out[1]‘ Upside down’)
     E
        I out[1].len == 12
           print(‘Invalid checksum’)
        E
           print(‘Invalid digit(s)’)

V barcodes = [

  ‘         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ’,
  ‘        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ’,
  ‘         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ’,
  ‘       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ’,
  ‘         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ’,
  ‘          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ’,
  ‘         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ’,
  ‘        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ’,
  ‘         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ’,
  ‘        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ’

]

L(barcode) barcodes

  decodeUPC(barcode)</lang>
Output:
[9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9]
[4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0]
[8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside down
[9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside down
Invalid digit(s)
[3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside down
[2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8]
[8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside down
[7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0]
[6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5]

ALGOL 68

<lang algol68>BEGIN

   # number of digits encoded by UPC                                         #
   INT upc digits = 12;
   # MODE to hold UPC bar code parse results                                 #
   MODE UPC = STRUCT( BOOL      valid         # TRUE if the UPC was valid,   #
                                              # FASLE otherwise              #
                    , [ 1 : upc digits ]INT digits
                                              # the digits encoded by the    #
                                              # UPC if it was valid          #
                    , BOOL      inverted      # TRUE if the code was scanned #
                                              # upside down, FALSE if it was #
                                              # right-side up                #
                    , STRING    error message # erro rmessage if the string  #
                                              # was invalid                  #
                    );
   # parses the UPC string s and returns a UPC containing the results        #
   PROC parse upc = ( STRING s )UPC:
        BEGIN
            # returns TRUE if we are at the end of s, FALSE otherwise        #
            PROC at end = BOOL: s pos > UPB s;
            # counts and skips spaces in s                                   #
            PROC skip spaces = INT:
                 BEGIN
                    INT spaces := 0;
                    WHILE IF at end THEN FALSE ELSE s[ s pos ] = " " FI DO
                        spaces +:= 1;
                        s pos  +:= 1
                    OD;
                    spaces
                 END; # skip spaces #
            # skips over the next number of bits characters of s and returns #
            # a bit representation ( space = 0, anything else = 1 )          #
            PROC get value = ( INT number of bits )BITS:
                 BEGIN
                    BITS value := 2r0;
                    FOR b TO number of bits WHILE NOT at end DO
                        value := ( value SHL 1 ) OR IF s[ s pos ] = " " THEN 2r0 ELSE 2r1 FI;
                        s pos +:= 1
                    OD;
                    value
                 END; # get value #
            # the representations of the digits                              #
            []BITS representations = ( 2r 0 0 0 1 1 0 1    # 0 #
                                     , 2r 0 0 1 1 0 0 1    # 1 #
                                     , 2r 0 0 1 0 0 1 1    # 2 #
                                     , 2r 0 1 1 1 1 0 1    # 3 #
                                     , 2r 0 1 0 0 0 1 1    # 4 #
                                     , 2r 0 1 1 0 0 0 1    # 5 #
                                     , 2r 0 1 0 1 1 1 1    # 6 #
                                     , 2r 0 1 1 1 0 1 1    # 7 #
                                     , 2r 0 1 1 0 1 1 1    # 8 #
                                     , 2r 0 0 0 1 0 1 1    # 9 #
                                     );
            []BITS reversed digits = ( 2r 0 1 0 0 1 1 1    # 0 #
                                     , 2r 0 1 1 0 0 1 1    # 1 #
                                     , 2r 0 0 1 1 0 1 1    # 2 #
                                     , 2r 0 1 0 0 0 0 1    # 3 #
                                     , 2r 0 0 1 1 1 0 1    # 4 #
                                     , 2r 0 1 1 1 0 0 1    # 5 #
                                     , 2r 0 0 0 0 1 0 1    # 6 #
                                     , 2r 0 0 1 0 0 0 1    # 7 #
                                     , 2r 0 0 0 1 0 0 1    # 8 #
                                     , 2r 0 0 1 0 1 1 1    # 9 #
                                     );
            # number of digits in the left and right sides of the UPC        #
            INT digits per side = upc digits OVER 2;
            UPC result;
            FOR d TO upc digits DO ( digits OF result )[ d ] := 0 OD;
            inverted OF result      := FALSE;
            error message OF result := "unknown error";
            valid OF result         := FALSE;
            INT s pos               := LWB s;
            IF skip spaces < 6 # should be 9 but we are being tolerant       #
            THEN
                # insufficient leading spaces                                #
                error message OF result := "missing leading spaces"
            ELIF get value( 3 ) /= 2r101 THEN
                # no start                                                   #
                error message OF result := "missing start sequence"
            ELSE
                # ok so far - should now have six digits, each encoded in    #
                # seven bits                                                 #
                # note we store the digits as 1..10 if the are right-sid up  #
                # and -1..-10 if they are inverted, so we can distinguish    #
                # right-side up 0 and inverted 0                             #
                # the digits are corrected to be 0..9 later                  #
                BOOL valid digits := TRUE;
                FOR d TO digits per side WHILE valid digits DO
                    BITS code = get value( 7 );
                    BOOL found digit := FALSE;
                    FOR d pos TO UPB representations WHILE NOT found digit DO
                        IF   code = representations[ d pos ] THEN
                            # found a "normal" digit                         #
                            found digit               := TRUE;
                            ( digits OF result )[ d ] := d pos
                        ELIF code = reversed digits[ d pos ] THEN
                            # found a reversed digit                         #
                            found digit               := TRUE;
                            inverted OF result        := TRUE;
                            ( digits OF result )[ d ] := - d pos
                        FI
                    OD;
                    IF NOT found digit THEN
                        # have an invalid digit                              #
                        error message OF result := "invalid digit " + whole( d, 0 );
                        valid digits := FALSE
                    FI
                OD;
                IF NOT valid digits THEN
                    # had an error                                           #
                    SKIP
                ELIF get value( 5 ) /= 2r01010 THEN
                    # no middle separator                                    #
                    error message OF result := "missing middle sequence"
                ELSE
                    # should now have 6 negated digits                      #
                    FOR d FROM digits per side + 1 TO upc digits WHILE valid digits DO
                        BITS code = NOT get value( 7 ) AND 16r7f;
                        BOOL found digit := FALSE;
                        FOR d pos TO UPB representations WHILE NOT found digit DO
                            IF  code = representations[ d pos ] THEN
                                # found a normal negated digit               #
                                found digit               := TRUE;
                                ( digits OF result )[ d ] := d pos
                            ELIF code = reversed digits[ d pos ] THEN
                                # found reversed negated digit               #
                                found digit               := TRUE;
                                inverted OF result        := TRUE;
                                ( digits OF result )[ d ] := - d pos
                            FI
                        OD;
                        IF NOT found digit THEN
                            # have an invalid digit                          #
                            error message OF result := "invalid digit " + whole( d, 0 );
                            valid digits            := FALSE
                        FI
                    OD;
                    IF NOT valid digits THEN
                        # had an error                                       #
                        SKIP
                    ELIF get value( 3 ) /= 2r101 THEN
                        # no end sequence                                    #
                        error message OF result := "missing end sequence"
                    ELIF skip spaces < 6 # should be 9 but we are being      #
                                         # tolerant                          #
                    THEN
                        # insufficient trailing spaces                       #
                        error message OF result := "insufficient trailing spaces"
                    ELIF NOT at end THEN
                        # extraneous stuff after the trailing spaces         #
                        error message OF result := "unexpected trailing bits"
                    ELSE
                        # valid so far - if there were reversed digits,      #
                        # check they were all reversed                       #
                        # and correct the digits to be in 0..9               #
                        BOOL all reversed  := TRUE;
                        FOR d TO upc digits DO
                            IF ( digits OF result )[ d ] < 0 THEN
                                # reversd digit                             #
                                ( digits OF result )[ d ]  := ABS ( digits OF result )[ d ] - 1
                            ELSE
                                # normal digit                               #
                                ( digits OF result )[ d ] -:= 1;
                                all reversed               := FALSE
                            FI
                        OD;
                        IF inverted OF result AND NOT all reversed
                        THEN
                            # had a mixture of inverted and non-inverted     #
                            # digits                                         #
                            error message OF result := "some reversed digits found"
                        ELSE
                            # the code appears valid - check the check sum   #
                            IF inverted OF result THEN
                                # the code was reversed - reverse the digits #
                                FOR d TO digits per side DO
                                    INT right digit
                                         = ( digits OF result )[ ( upc digits + 1 ) - d ];
                                    ( digits OF result )[ ( upc digits + 1 ) - d ]
                                        := ( digits OF result )[ d ];
                                    ( digits OF result )[ d ] := right digit
                                OD
                            FI;
                            INT check sum := 0;
                            FOR d FROM 1 BY 2 TO upc digits DO check sum +:= 3 * ( digits OF result )[ d ] OD;
                            FOR d FROM 2 BY 2 TO upc digits DO check sum +:=     ( digits OF result )[ d ] OD;
                            IF check sum MOD 10 /= 0 THEN
                                # invalid check digit                        #
                                error message OF result := "incorrect check digit"
                            ELSE
                                # the UPC code appears valid                 #
                                valid OF result         := TRUE
                            FI
                        FI
                    FI
                FI
            FI;
            result
        END; # parse upc #
   # task test cases                                                         #
   []STRING tests =

( " # # # ## # ## # ## ### ## ### ## #### # # # ## ## # # ## ## ### # ## ## ### # # # " , " # # # ## ## # #### # # ## # ## # ## # # # ### # ### ## ## ### # # ### ### # # # " , " # # # # # ### # # # # # # # # # # ## # ## # ## # ## # # #### ### ## # # " , " # # ## ## ## ## # # # # ### # ## ## # # # ## ## # ### ## ## # # #### ## # # # " , " # # ### ## # ## ## ### ## # ## # # ## # # ### # ## ## # # ### # ## ## # # # " , " # # # # ## ## # # # # ## ## # # # # # #### # ## # #### #### # # ## # #### # # " , " # # # ## ## # # ## ## # ### ## ## # # # # # # # # ### # # ### # # # # # " , " # # # # ## ## # # ## ## ### # # # # # ### ## ## ### ## ### ### ## # ## ### ## # # " , " # # ### ## ## # # #### # ## # #### # #### # # # # # ### # # ### # # # ### # # # " , " # # # #### ## # #### # # ## ## ### #### # # # # ### # ### ### # # ### # # # ### # # " );

   FOR t pos FROM LWB tests TO UPB tests DO
       UPC code = parse upc( tests[ t pos ] );
       print( ( whole( t pos, -2 ), ":" ) );
       IF NOT valid OF code THEN
           # invalid UPC code                                                #
           print( ( "                       error: ", error message OF code, newline ) )
       ELSE
           # valid code                                                      #
           FOR d TO upc digits - 1 DO print( ( whole( ( digits OF code )[ d ], -2 ) ) ) OD;
           print( ( " valid" ) );
           IF inverted OF code THEN print( ( " (inverted)" ) ) FI;
           print( ( newline ) )
       FI
   OD

END</lang>

Output:
 1: 9 2 4 7 7 3 2 7 1 0 1 valid
 2: 4 0 3 9 4 4 4 4 1 0 5 valid
 3: 8 3 4 9 9 9 6 7 6 7 0 valid (inverted)
 4: 9 3 9 8 2 5 1 5 8 8 1 valid (inverted)
 5:                       error: invalid digit 12
 6: 3 1 6 3 1 3 7 1 8 7 1 valid (inverted)
 7: 2 1 4 5 7 5 8 7 5 6 0 valid
 8: 8 1 8 7 7 8 8 4 1 8 1 valid (inverted)
 9: 7 0 6 4 6 6 7 4 3 0 3 valid
10: 6 5 3 4 8 3 5 4 0 4 3 valid

AutoHotkey

<lang AutoHotkey>UPC2Dec(code){

   lBits :={"   ## #":0,"  ##  #":1,"  #  ##":2," #### #":3," #   ##":4," ##   #":5," # ####":6," ### ##":7," ## ###":8,"   # ##":9}
   xlBits:={"# ##   ":0,"#  ##  ":1,"##  #  ":2,"# #### ":3,"##   # ":4,"#   ## ":5,"#### # ":6,"## ### ":7,"### ## ":8,"## #   ":9}
   rBits :={"###  # ":0,"##  ## ":1,"## ##  ":2,"#    # ":3,"# ###  ":4,"#  ### ":5,"# #    ":6,"#   #  ":7,"#  #   ":8,"### #  ":9}
   xrBits:={" #  ###":0," ##  ##":1,"  ## ##":2," #    #":3,"  ### #":4," ###  #":5,"    # #":6,"  #   #":7,"   #  #":8,"  # ###":9}
   UPC := "", CD := 0,	code := Trim(code, " ")
   S := SubStr(code, 1, 3), code := SubStr(code, 4)			; start or "upside down" end sequence
   loop 6
       C := SubStr(code, 1, 7), code := SubStr(code, 8)		; six left hand or "upside down" right hand digits
       , UPC := lBits[C] <> "" ? UPC . lBits[C] : xrBits[C] . UPC
   M := SubStr(code, 1, 5), code := SubStr(code, 6)			; middle sequence
   loop 6
       C := SubStr(code, 1, 7), code := SubStr(code, 8)		; six right hand or "upside down" left hand digits
       , UPC := rBits[C] <> "" ? UPC . rBits[C] : xlBits[C] . UPC
   E := SubStr(code, 1, 3), code := SubStr(code, 4)			; end or "upside down" start sequence
   for k, v in StrSplit(UPC)
       CD += Mod(A_Index, 2) ? v*3 : v					; Check Digit
   if (S <> "# #") || (M <> " # # ") || (E <> "# #") || Mod(CD, 10)
       return "Invalid!"
   return UPC

} </lang> Examples:<lang AutoHotkey>data = (

        # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #         
        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         
        # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         
        # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #         
        # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #         
        # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         
        # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #         
        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         
        # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #         
        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         

) for i, code in StrSplit(data, "`n", "`r")

   output .= i ":`t" UPC2Dec(code) "`n"

MsgBox, 262144, ,% output return</lang>

Output:
1:	924773271019
2:	403944441050
3:	834999676706
4:	939825158811
5:	Invalid!
6:	316313718717
7:	214575875608
8:	818778841813
9:	706466743030
10:	653483540435

AWK

<lang AWK>

  1. syntax: GAWK -f UPC.AWK

BEGIN {

   ls_arr["   ## #"] = 0
   ls_arr["  ##  #"] = 1
   ls_arr["  #  ##"] = 2
   ls_arr[" #### #"] = 3
   ls_arr[" #   ##"] = 4
   ls_arr[" ##   #"] = 5
   ls_arr[" # ####"] = 6
   ls_arr[" ### ##"] = 7
   ls_arr[" ## ###"] = 8
   ls_arr["   # ##"] = 9
   for (i in ls_arr) {
     tmp = i
     gsub(/#/,"x",tmp)
     gsub(/ /,"#",tmp)
     gsub(/x/," ",tmp)
     rs_arr[tmp] = ls_arr[i]
   }
   split("3,1,3,1,3,1,3,1,3,1,3,1",weight_arr,",")
   bc_arr[++n] = "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       "
   bc_arr[++n] = "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         "
   bc_arr[++n] = "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         "
   bc_arr[++n] = "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        "
   bc_arr[++n] = "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          "
   bc_arr[++n] = "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         "
   bc_arr[++n] = "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        "
   bc_arr[++n] = "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         "
   bc_arr[++n] = "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       "
   bc_arr[++n] = "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         "
   bc_arr[++n] = "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### #" # NG
   tmp = "123456712345671234567123456712345671234567"
   printf("%2s: %-18s---%s-----%s---\n","N","UPC-A",tmp,tmp) # heading
   for (i=1; i<=n; i++) {
  1. accept any number of spaces at beginning or end; I.E. minimum of 9 is not enforced
     sub(/^ +/,"",bc_arr[i])
     sub(/ +$/,"",bc_arr[i])
     bc = bc_arr[i]
     if (length(bc) == 95 && substr(bc,1,3) == "# #" && substr(bc,46,5) == " # # " && substr(bc,93,3) == "# #") {
       upc = ""
       sum = upc_build(ls_arr,1,substr(bc,4,42))
       sum += upc_build(rs_arr,7,substr(bc,51,42))
       if (upc ~ /^x+$/) { msg = "reversed" }
       else if (upc ~ /x/) { msg = "invalid digit(s)" }
       else if (sum % 10 != 0) { msg = "bad check digit" }
       else { msg = upc }
     }
     else {
       msg = "invalid format"
     }
     printf("%2d: %-18s%s\n",i,msg,bc)
   }
   exit(0)

} function upc_build(arr,pos,bc, i,s,sum) {

   pos--
   for (i=1; i<=42; i+=7) {
     s = substr(bc,i,7)
     pos++
     if (s in arr) {
       upc = upc arr[s]
       sum += arr[s] * weight_arr[pos]
     }
     else {
       upc = upc "x"
     }
   }
   return(sum)

} </lang>

Output:
 N: UPC-A             ---123456712345671234567123456712345671234567-----123456712345671234567123456712345671234567---
 1: 924773271019      # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #
 2: 403944441050      # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #
 3: reversed          # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #
 4: reversed          # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #
 5: invalid digit(s)  # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #
 6: reversed          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #
 7: 214575875608      # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #
 8: reversed          # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #
 9: 706466743030      # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #
10: 653483540435      # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #
11: invalid format    # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### #

C

<lang c>#include <stdbool.h>

  1. include <stdio.h>
  2. include <stdlib.h>
  3. include <string.h>

typedef char const *const string;

bool consume_sentinal(bool middle, string s, size_t *pos) {

   if (middle) {
       if (s[*pos] == ' ' && s[*pos + 1] == '#' && s[*pos + 2] == ' ' && s[*pos + 3] == '#' && s[*pos + 4] == ' ') {
           *pos += 5;
           return true;
       }
   } else {
       if (s[*pos] == '#' && s[*pos + 1] == ' ' && s[*pos + 2] == '#') {
           *pos += 3;
           return true;
       }
   }
   return false;

}

int consume_digit(bool right, string s, size_t *pos) {

   const char zero = right ? '#' : ' ';
   const char one = right ? ' ' : '#';
   size_t i = *pos;
   int result = -1;
   if (s[i] == zero) {
       if (s[i + 1] == zero) {
           if (s[i + 2] == zero) {
               if (s[i + 3] == one) {
                   if (s[i + 4] == zero) {
                       if (s[i + 5] == one && s[i + 6] == one) {
                           result = 9;
                       }
                   } else if (s[i + 4] == one) {
                       if (s[i + 5] == zero && s[i + 6] == one) {
                           result = 0;
                       }
                   }
               }
           } else if (s[i + 2] == one) {
               if (s[i + 3] == zero) {
                   if (s[i + 4] == zero && s[i + 5] == one && s[i + 6] == one) {
                       result = 2;
                   }
               } else if (s[i + 3] == one) {
                   if (s[i + 4] == zero && s[i + 5] == zero && s[i + 6] == one) {
                       result = 1;
                   }
               }
           }
       } else if (s[i + 1] == one) {
           if (s[i + 2] == zero) {
               if (s[i + 3] == zero) {
                   if (s[i + 4] == zero && s[i + 5] == one && s[i + 6] == one) {
                       result = 4;
                   }
               } else if (s[i + 3] == one) {
                   if (s[i + 4] == one && s[i + 5] == one && s[i + 6] == one) {
                       result = 6;
                   }
               }
           } else if (s[i + 2] == one) {
               if (s[i + 3] == zero) {
                   if (s[i + 4] == zero) {
                       if (s[i + 5] == zero && s[i + 6] == one) {
                           result = 5;
                       }
                   } else if (s[i + 4] == one) {
                       if (s[i + 5] == one && s[i + 6] == one) {
                           result = 8;
                       }
                   }
               } else if (s[i + 3] == one) {
                   if (s[i + 4] == zero) {
                       if (s[i + 5] == one && s[i + 6] == one) {
                           result = 7;
                       }
                   } else if (s[i + 4] == one) {
                       if (s[i + 5] == zero && s[i + 6] == one) {
                           result = 3;
                       }
                   }
               }
           }
       }
   }
   if (result >= 0) {
       *pos += 7;
   }
   return result;

}

bool decode_upc(string src, char *buffer) {

   const int one = 1;
   const int three = 3;
   size_t pos = 0;
   int sum = 0;
   int digit;
   //1) 9 spaces (unreliable)
   while (src[pos] != '#') {
       if (src[pos] == 0) {
           return false;
       }
       pos++;
   }
   //2) Start "# #"
   if (!consume_sentinal(false, src, &pos)) {
       return false;
   }
   //3) 6 left-hand digits (space is zero and hash is one)
   digit = consume_digit(false, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += three * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(false, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += one * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(false, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += three * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(false, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += one * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(false, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += three * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(false, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += one * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   //4) Middle "# #"
   if (!consume_sentinal(true, src, &pos)) {
       return false;
   }
   //5) 6 right-hand digits (hash is zero and space is one)
   digit = consume_digit(true, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += three * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(true, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += one * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(true, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += three * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(true, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += one * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(true, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += three * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   digit = consume_digit(true, src, &pos);
   if (digit < 0) {
       return false;
   }
   sum += one * digit;
   *buffer++ = digit + '0';
   *buffer++ = ' ';
   //6) Final "# #"
   if (!consume_sentinal(false, src, &pos)) {
       return false;
   }
   //7) 9 spaces (unreliable)
   // skip
   //8) the dot product of the number and (3, 1)+ sequence mod 10 must be zero
   return sum % 10 == 0;

}

void test(string src) {

   char buffer[24];
   if (decode_upc(src, buffer)) {
       buffer[22] = 0;
       printf("%sValid\n", buffer);
   } else {
       size_t len = strlen(src);
       char *rev = malloc(len + 1);
       size_t i;
       if (rev == NULL) {
           exit(1);
       }
       for (i = 0; i < len; i++) {
           rev[i] = src[len - i - 1];
       }
  1. pragma warning(push)
  2. pragma warning(disable : 6386)
       // if len + 1 bytes are allocated, and len bytes are writable, there is no buffer overrun
       rev[len] = 0;
  1. pragma warning(pop)
       if (decode_upc(rev, buffer)) {
           buffer[22] = 0;
           printf("%sValid (upside down)\n", buffer);
       } else {
           printf("Invalid digit(s)\n");
       }
       free(rev);
   }

}

int main() {

   int num = 0;
   printf("%2d: ", ++num);
   test("         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ");
   printf("%2d: ", ++num);
   test("        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ");
   printf("%2d: ", ++num);
   test("         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ");
   printf("%2d: ", ++num);
   test("       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ");
   printf("%2d: ", ++num);
   test("         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ");
   printf("%2d: ", ++num);
   test("          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ");
   printf("%2d: ", ++num);
   test("         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ");
   printf("%2d: ", ++num);
   test("        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ");
   printf("%2d: ", ++num);
   test("         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ");
   printf("%2d: ", ++num);
   test("        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ");
   return 0;

}</lang>

Output:
 1: 9 2 4 7 7 3 2 7 1 0 1 Valid
 2: 4 0 3 9 4 4 4 4 1 0 5 Valid
 3: 8 3 4 9 9 9 6 7 6 7 0 Valid (upside down)
 4: 9 3 9 8 2 5 1 5 8 8 1 Valid (upside down)
 5: Invalid digit(s)
 6: 3 1 6 3 1 3 7 1 8 7 1 Valid (upside down)
 7: 2 1 4 5 7 5 8 7 5 6 0 Valid
 8: 8 1 8 7 7 8 8 4 1 8 1 Valid (upside down)
 9: 7 0 6 4 6 6 7 4 3 0 3 Valid
10: 6 5 3 4 8 3 5 4 0 4 3 Valid

C++

Translation of: Kotlin

<lang cpp>#include <iostream>

  1. include <locale>
  2. include <map>
  3. include <vector>

std::string trim(const std::string &str) {

   auto s = str;
   //rtrim
   auto it1 = std::find_if(s.rbegin(), s.rend(), [](char ch) { return !std::isspace<char>(ch, std::locale::classic()); });
   s.erase(it1.base(), s.end());
   //ltrim
   auto it2 = std::find_if(s.begin(), s.end(), [](char ch) { return !std::isspace<char>(ch, std::locale::classic()); });
   s.erase(s.begin(), it2);
   return s;

}

template <typename T> std::ostream &operator<<(std::ostream &os, const std::vector<T> &v) {

   auto it = v.cbegin();
   auto end = v.cend();
   os << '[';
   if (it != end) {
       os << *it;
       it = std::next(it);
   }
   while (it != end) {
       os << ", " << *it;
       it = std::next(it);
   }
   return os << ']';

}

const std::map<std::string, int> LEFT_DIGITS = {

   {"   ## #", 0},
   {"  ##  #", 1},
   {"  #  ##", 2},
   {" #### #", 3},
   {" #   ##", 4},
   {" ##   #", 5},
   {" # ####", 6},
   {" ### ##", 7},
   {" ## ###", 8},
   {"   # ##", 9}

};

const std::map<std::string, int> RIGHT_DIGITS = {

   {"###  # ", 0},
   {"##  ## ", 1},
   {"## ##  ", 2},
   {"#    # ", 3},
   {"# ###  ", 4},
   {"#  ### ", 5},
   {"# #    ", 6},
   {"#   #  ", 7},
   {"#  #   ", 8},
   {"### #  ", 9}

};

const std::string END_SENTINEL = "# #"; const std::string MID_SENTINEL = " # # ";

void decodeUPC(const std::string &input) {

   auto decode = [](const std::string &candidate) {
       using OT = std::vector<int>;
       OT output;
       size_t pos = 0;
       auto part = candidate.substr(pos, END_SENTINEL.length());
       if (part == END_SENTINEL) {
           pos += END_SENTINEL.length();
       } else {
           return std::make_pair(false, OT{});
       }
       for (size_t i = 0; i < 6; i++) {
           part = candidate.substr(pos, 7);
           pos += 7;
           auto e = LEFT_DIGITS.find(part);
           if (e != LEFT_DIGITS.end()) {
               output.push_back(e->second);
           } else {
               return std::make_pair(false, output);
           }
       }
       part = candidate.substr(pos, MID_SENTINEL.length());
       if (part == MID_SENTINEL) {
           pos += MID_SENTINEL.length();
       } else {
           return std::make_pair(false, OT{});
       }
       for (size_t i = 0; i < 6; i++) {
           part = candidate.substr(pos, 7);
           pos += 7;
           auto e = RIGHT_DIGITS.find(part);
           if (e != RIGHT_DIGITS.end()) {
               output.push_back(e->second);
           } else {
               return std::make_pair(false, output);
           }
       }
       part = candidate.substr(pos, END_SENTINEL.length());
       if (part == END_SENTINEL) {
           pos += END_SENTINEL.length();
       } else {
           return std::make_pair(false, OT{});
       }
       int sum = 0;
       for (size_t i = 0; i < output.size(); i++) {
           if (i % 2 == 0) {
               sum += 3 * output[i];
           } else {
               sum += output[i];
           }
       }
       return std::make_pair(sum % 10 == 0, output);
   };
   auto candidate = trim(input);
   auto out = decode(candidate);
   if (out.first) {
       std::cout << out.second << '\n';
   } else {
       std::reverse(candidate.begin(), candidate.end());
       out = decode(candidate);
       if (out.first) {
           std::cout << out.second << " Upside down\n";
       } else if (out.second.size()) {
           std::cout << "Invalid checksum\n";
       } else {
           std::cout << "Invalid digit(s)\n";
       }
   }

}

int main() {

   std::vector<std::string> barcodes = {
       "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
       "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
       "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
       "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
       "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
       "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
       "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
       "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
       "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
       "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ",
   };
   for (auto &barcode : barcodes) {
       decodeUPC(barcode);
   }
   return 0;

}</lang>

Output:
[9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9]
[4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0]
[8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside down
[9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside down
Invalid digit(s)
[3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside down
[2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8]
[8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside down
[7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0]
[6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5]

D

Translation of: C++

<lang d>import std.algorithm : countUntil, each, map; import std.array : array; import std.conv : to; import std.range : empty, retro; import std.stdio : writeln; import std.string : strip; import std.typecons : tuple;

immutable LEFT_DIGITS = [

   "   ## #",
   "  ##  #",
   "  #  ##",
   " #### #",
   " #   ##",
   " ##   #",
   " # ####",
   " ### ##",
   " ## ###",
   "   # ##"

]; immutable RIGHT_DIGITS = LEFT_DIGITS.map!`a.map!"a == '#' ? ' ' : '#'".array`.array;

immutable END_SENTINEL = "# #"; immutable MID_SENTINEL = " # # ";

void decodeUPC(string input) {

   auto decode(string candidate) {
       int[] output;
       size_t pos = 0;
       auto next = pos + END_SENTINEL.length;
       auto part = candidate[pos .. next];
       if (part == END_SENTINEL) {
           pos = next;
       } else {
           return tuple(false, cast(int[])[]);
       }
       foreach (_; 0..6) {
           next = pos + 7;
           part = candidate[pos .. next];
           auto i = countUntil(LEFT_DIGITS, part);
           if (i >= 0) {
               output ~= i;
               pos = next;
           } else {
               return tuple(false, cast(int[])[]);
           }
       }
       next = pos + MID_SENTINEL.length;
       part = candidate[pos .. next];
       if (part == MID_SENTINEL) {
           pos = next;
       } else {
           return tuple(false, cast(int[])[]);
       }
       foreach (_; 0..6) {
           next = pos + 7;
           part = candidate[pos .. next];
           auto i = countUntil(RIGHT_DIGITS, part);
           if (i >= 0) {
               output ~= i;
               pos = next;
           } else {
               return tuple(false, cast(int[])[]);
           }
       }
       next = pos + END_SENTINEL.length;
       part = candidate[pos .. next];
       if (part == END_SENTINEL) {
           pos = next;
       } else {
           return tuple(false, cast(int[])[]);
       }
       int sum = 0;
       foreach (i,v; output) {
           if (i % 2 == 0) {
               sum += 3 * v;
           } else {
               sum += v;
           }
       }
       return tuple(sum % 10 == 0, output);
   }
   auto candidate = input.strip;
   auto output = decode(candidate);
   if (output[0]) {
       writeln(output[1]);
   } else {
       output = decode(candidate.retro.array.to!string);
       if (output[0]) {
           writeln(output[1], " Upside down");
       } else if (output[1].empty) {
           writeln("Invalid digit(s)");
       } else {
           writeln("Invalid checksum", output);
       }
   }

}

void main() {

   auto barcodes = [
       "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
       "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
       "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
       "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
       "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
       "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
       "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
       "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
       "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
       "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ",
   ];
   barcodes.each!decodeUPC;

}</lang>

Output:
[9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9]
[4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0]
[8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside down
[9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside down
Invalid digit(s)
[3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside down
[2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8]
[8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside down
[7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0]
[6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5]

Factor

Works with: Factor version 0.99 2019-10-06

<lang factor>USING: combinators combinators.short-circuit formatting grouping kernel locals math math.functions math.vectors sequences sequences.repeating unicode ;

CONSTANT: numbers {

   "   ## #"
   "  ##  #"
   "  #  ##"
   " #### #"
   " #   ##"
   " ##   #"
   " # ####"
   " ### ##"
   " ## ###"
   "   # ##"

}

upc>dec ( str -- seq )
   [ blank? ] trim 3 tail 3 head* 42 cut 5 tail
   [ 35 = 32 35 ? ] map append 7 group [ numbers index ] map ;
valid-digits? ( seq -- ? ) [ f = ] none? ;
valid-checksum? ( seq -- ? )
   { 3 1 } 12 cycle v* sum 10 divisor? ;
valid-upc? ( seq -- ? )
   { [ valid-digits? ] [ valid-checksum? ] } 1&& ;
process-upc ( upc -- obj upside-down? )
   upc upc>dec :> d
   {
       { [ d valid-upc? ] [ d f ] }
       { [ upc reverse upc>dec dup valid-upc? ] [ t ] }
       { [ drop d valid-digits? ] [ "Invalid checksum" f ] }
       [ "Invalid digit(s)" f ]
   } cond ;

{

"         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       "
 "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #      "
"         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #       "
  "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        "
"         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #       "

" # # # # ## ## # # # # ## ## # # # # # #### # ## # #### #### # # ## # #### # # "

"         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #     "
 "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #      "
"         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       "
 "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #      "

} [ process-upc "(upside down)" "" ? "%u %s\n" printf ] each</lang>

Output:
{ 9 2 4 7 7 3 2 7 1 0 1 9 }
{ 4 0 3 9 4 4 4 4 1 0 5 0 }
{ 8 3 4 9 9 9 6 7 6 7 0 6 } (upside down)
{ 9 3 9 8 2 5 1 5 8 8 1 1 } (upside down)
"Invalid digit(s)" 
{ 3 1 6 3 1 3 7 1 8 7 1 7 } (upside down)
{ 2 1 4 5 7 5 8 7 5 6 0 8 }
{ 8 1 8 7 7 8 8 4 1 8 1 3 } (upside down)
{ 7 0 6 4 6 6 7 4 3 0 3 0 }
{ 6 5 3 4 8 3 5 4 0 4 3 5 }

Go

<lang go>package main

import (

   "fmt"
   "regexp"

)

var bits = []string{

   "0 0 0 1 1 0 1 ",
   "0 0 1 1 0 0 1 ",
   "0 0 1 0 0 1 1 ",
   "0 1 1 1 1 0 1 ",
   "0 1 0 0 0 1 1 ",
   "0 1 1 0 0 0 1 ",
   "0 1 0 1 1 1 1 ",
   "0 1 1 1 0 1 1 ",
   "0 1 1 0 1 1 1 ",
   "0 0 0 1 0 1 1 ",

}

var (

   lhs = make(map[string]int)
   rhs = make(map[string]int)

)

var weights = []int{3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1}

const (

   s = "# #"
   m = " # # "
   e = "# #"
   d = "(?:#| ){7}"

)

func init() {

   for i := 0; i <= 9; i++ {
       lt := make([]byte, 7)
       rt := make([]byte, 7)
       for j := 0; j < 14; j += 2 {
           if bits[i][j] == '1' {
               lt[j/2] = '#'
               rt[j/2] = ' '
           } else {
               lt[j/2] = ' '
               rt[j/2] = '#'
           }
       }
       lhs[string(lt)] = i
       rhs[string(rt)] = i
   }

}

func reverse(s string) string {

   b := []byte(s)
   for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {
       b[i], b[j] = b[j], b[i]
   }
   return string(b)

}

func main() {

   barcodes := []string{
       "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
       "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
       "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
       "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
       "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
       "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
       "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
       "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
       "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
       "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ",
   }
   // Regular expression to check validity of a barcode and extract digits. However we accept any number
   // of spaces at the beginning or end i.e. we don't enforce a minimum of 9.
   expr := fmt.Sprintf(`^\s*%s(%s)(%s)(%s)(%s)(%s)(%s)%s(%s)(%s)(%s)(%s)(%s)(%s)%s\s*$`,
       s, d, d, d, d, d, d, m, d, d, d, d, d, d, e)
   rx := regexp.MustCompile(expr)
   fmt.Println("UPC-A barcodes:")
   for i, bc := range barcodes {
       for j := 0; j <= 1; j++ {
           if !rx.MatchString(bc) {
               fmt.Printf("%2d: Invalid format\n", i+1)
               break
           }
           codes := rx.FindStringSubmatch(bc)
           digits := make([]int, 12)
           var invalid, ok bool // False by default.
           for i := 1; i <= 6; i++ {
               digits[i-1], ok = lhs[codes[i]]
               if !ok {
                   invalid = true
               }
               digits[i+5], ok = rhs[codes[i+6]]
               if !ok {
                   invalid = true
               }
           }
           if invalid { // Contains at least one invalid digit.
               if j == 0 { // Try reversing.
                   bc = reverse(bc)
                   continue
               } else {
                   fmt.Printf("%2d: Invalid digit(s)\n", i+1)
                   break
               }
           }
           sum := 0
           for i, d := range digits {
               sum += weights[i] * d
           }
           if sum%10 != 0 {
               fmt.Printf("%2d: Checksum error\n", i+1)
               break
           } else {
               ud := ""
               if j == 1 {
                   ud = "(upside down)"
               }
               fmt.Printf("%2d: %v %s\n", i+1, digits, ud)
               break
           }
       }
   }

}</lang>

Output:
UPC-A barcodes:
 1: [9 2 4 7 7 3 2 7 1 0 1 9] 
 2: [4 0 3 9 4 4 4 4 1 0 5 0] 
 3: [8 3 4 9 9 9 6 7 6 7 0 6] (upside down)
 4: [9 3 9 8 2 5 1 5 8 8 1 1] (upside down)
 5: Invalid digit(s)
 6: [3 1 6 3 1 3 7 1 8 7 1 7] (upside down)
 7: [2 1 4 5 7 5 8 7 5 6 0 8] 
 8: [8 1 8 7 7 8 8 4 1 8 1 3] (upside down)
 9: [7 0 6 4 6 6 7 4 3 0 3 0] 
10: [6 5 3 4 8 3 5 4 0 4 3 5] 

J

Implementation:

<lang J>upcdigit=:".;._2]0 :0

 0 0 0 1 1 0 1 NB. 0
 0 0 1 1 0 0 1 NB. 1
 0 0 1 0 0 1 1 NB. 2
 0 1 1 1 1 0 1 NB. 3
 0 1 0 0 0 1 1 NB. 4
 0 1 1 0 0 0 1 NB. 5
 0 1 0 1 1 1 1 NB. 6
 0 1 1 1 0 1 1 NB. 7
 0 1 1 0 1 1 1 NB. 8
 0 0 0 1 0 1 1 NB. 9

)

upc2dec=:3 :0

 if. 95~: #code=. '#'=dtb dlb y do._ return.end.
 if. (11$1 0) ~: 0 1 2 45 46 47 48 49 92 93 94{ code do._ return. end.
 digits=. <./([:,upcdigit i.0 1~:(3 50+/i.6 7) {  ])"1 code,:|.code
 if. 10 e.digits do._ return.end.
 if.0 ~:10|digits+/ .* 12$3 1 do._ return.end.

)</lang>

Here, we perform some basic integrity checks and use a table lookup to identify the decimal digits.

Task example:

<lang J>barcodes=:0 :0

        # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       
       # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         
        # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         
      # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        
        # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          
         # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         
        # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        
       # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         
        # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       
       # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         

)

  upc2dec;._2 barcodes

9 2 4 7 7 3 2 7 1 0 1 9 4 0 3 9 4 4 4 4 1 0 5 0 8 3 4 9 9 9 6 7 6 7 0 6 9 3 9 8 2 5 1 5 8 8 1 1 _ 0 0 0 0 0 0 0 0 0 0 0 3 1 6 3 1 3 7 1 8 7 1 7 2 1 4 5 7 5 8 7 5 6 0 8 8 1 8 7 7 8 8 4 1 8 1 3 7 0 6 4 6 6 7 4 3 0 3 0 6 5 3 4 8 3 5 4 0 4 3 5 </lang>

The row which begins with _ is the damaged row. (If rescanning did not fix that problem, the operator would have to enter the code manually.)

It may be desirable to format the result differently, but that's currently not a part of the task definition.

Java

Translation of: Kotlin

<lang java>import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.function.Consumer; import java.util.function.Function; import java.util.stream.Collectors;

public class UPC {

   private static final int SEVEN = 7;
   private static final Map<String, Integer> LEFT_DIGITS = Map.of(
       "   ## #", 0,
       "  ##  #", 1,
       "  #  ##", 2,
       " #### #", 3,
       " #   ##", 4,
       " ##   #", 5,
       " # ####", 6,
       " ### ##", 7,
       " ## ###", 8,
       "   # ##", 9
   );
   private static final Map<String, Integer> RIGHT_DIGITS = LEFT_DIGITS.entrySet()
       .stream()
       .collect(Collectors.toMap(
           entry -> entry.getKey()
               .replace(' ', 's')
               .replace('#', ' ')
               .replace('s', '#'),
           Map.Entry::getValue
       ));
   private static final String END_SENTINEL = "# #";
   private static final String MID_SENTINEL = " # # ";
   private static void decodeUPC(String input) {
       Function<String, Map.Entry<Boolean, List<Integer>>> decode = (String candidate) -> {
           int pos = 0;
           var part = candidate.substring(pos, pos + END_SENTINEL.length());
           List<Integer> output = new ArrayList<>();
           if (END_SENTINEL.equals(part)) {
               pos += END_SENTINEL.length();
           } else {
               return Map.entry(false, output);
           }
           for (int i = 1; i < SEVEN; i++) {
               part = candidate.substring(pos, pos + SEVEN);
               pos += SEVEN;
               if (LEFT_DIGITS.containsKey(part)) {
                   output.add(LEFT_DIGITS.get(part));
               } else {
                   return Map.entry(false, output);
               }
           }
           part = candidate.substring(pos, pos + MID_SENTINEL.length());
           if (MID_SENTINEL.equals(part)) {
               pos += MID_SENTINEL.length();
           } else {
               return Map.entry(false, output);
           }
           for (int i = 1; i < SEVEN; i++) {
               part = candidate.substring(pos, pos + SEVEN);
               pos += SEVEN;
               if (RIGHT_DIGITS.containsKey(part)) {
                   output.add(RIGHT_DIGITS.get(part));
               } else {
                   return Map.entry(false, output);
               }
           }
           part = candidate.substring(pos, pos + END_SENTINEL.length());
           if (!END_SENTINEL.equals(part)) {
               return Map.entry(false, output);
           }
           int sum = 0;
           for (int i = 0; i < output.size(); i++) {
               if (i % 2 == 0) {
                   sum += 3 * output.get(i);
               } else {
                   sum += output.get(i);
               }
           }
           return Map.entry(sum % 10 == 0, output);
       };
       Consumer<List<Integer>> printList = list -> {
           var it = list.iterator();
           System.out.print('[');
           if (it.hasNext()) {
               System.out.print(it.next());
           }
           while (it.hasNext()) {
               System.out.print(", ");
               System.out.print(it.next());
           }
           System.out.print(']');
       };
       var candidate = input.trim();
       var out = decode.apply(candidate);
       if (out.getKey()) {
           printList.accept(out.getValue());
           System.out.println();
       } else {
           StringBuilder builder = new StringBuilder(candidate);
           builder.reverse();
           out = decode.apply(builder.toString());
           if (out.getKey()) {
               printList.accept(out.getValue());
               System.out.println(" Upside down");
           } else if (out.getValue().size() == 12) {
               System.out.println("Invalid checksum");
           } else {
               System.out.println("Invalid digit(s)");
           }
       }
   }
   public static void main(String[] args) {
       var barcodes = List.of(
           "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
           "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
           "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
           "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
           "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
           "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
           "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
           "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
           "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
           "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         "
       );
       barcodes.forEach(UPC::decodeUPC);
   }

}</lang>

Output:
[9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9]
[4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0]
[8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside down
[9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside down
Invalid digit(s)
[3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside down
[2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8]
[8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside down
[7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0]
[6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5]

Julia

Translation of: Raku

<lang julia>const pat1 = (" ## #", " ## #", " # ##", " #### #", " # ##",

             " ##   #", " # ####", " ### ##", " ## ###", "   # ##")

const pat2 = [replace(x, r"[# ]" => (x) -> x == " " ? "#" : " ") for x in pat1] const ptod1 = Dict((b => a - 1) for (a, b) in enumerate(pat1)) const ptod2 = Dict((b => a - 1) for (a, b) in enumerate(pat2)) const reg = Regex("^\\s*# #\\s*((?:" * join(pat1, "|") *

                 "){6})\\s*# #\\s*((?:" * join(pat2, "|") * "){6})\\s*# #\\s*")

const lines = [

"         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
 "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #      ",
"         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #       ",
  "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
"         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #       ",

" # # # # ## ## # # # # ## ## # # # # # #### # ## # #### #### # # ## # #### # # ",

"         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #     ",
 "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #      ",
"         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
 "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #      ",

]

function decodeUPC(line)

   if (m = match(reg, line)) != nothing
       mats, dig = filter(!isempty, m.captures), Int[]
       for mat in mats
           append!(dig, [ptod1[x.match] for x in eachmatch(r"(.......)", mat)
               if haskey(ptod1, x.match)])
           append!(dig, [ptod2[x.match] for x in eachmatch(r"(.......)", mat)
               if haskey(ptod2, x.match)])
       end
       dsum = sum([(isodd(i) ? 3 : 1) * n for (i, n) in enumerate(dig)])
       (dsum % 10 == 0) && return prod(string.(dig))
   end
   return ""

end

for line in lines

   println((s = decodeUPC(line)) != "" ? s :
           (s = decodeUPC(reverse(line))) != "" ? s : "Invalid")

end

</lang>

Output:
924773271019
403944441050
834999676706
939825158811
Invalid
316313718717
214575875608
818778841813
706466743030
653483540435

Kotlin

Translation of: C

<lang scala>val LEFT_DIGITS = mapOf(

   "   ## #" to 0,
   "  ##  #" to 1,
   "  #  ##" to 2,
   " #### #" to 3,
   " #   ##" to 4,
   " ##   #" to 5,
   " # ####" to 6,
   " ### ##" to 7,
   " ## ###" to 8,
   "   # ##" to 9

) val RIGHT_DIGITS = LEFT_DIGITS.mapKeys {

   it.key.replace(' ', 's').replace('#', ' ').replace('s', '#')

}

const val END_SENTINEL = "# #" const val MID_SENTINEL = " # # "

fun decodeUPC(input: String) {

   fun decode(candidate: String): Pair<Boolean, List<Int>> {
       var pos = 0
       var part = candidate.slice(pos until pos + END_SENTINEL.length)
       if (part == END_SENTINEL) {
           pos += END_SENTINEL.length
       } else {
           return Pair(false, emptyList())
       }
       val output = mutableListOf<Int>()
       for (i in 0 until 6) {
           part = candidate.slice(pos until pos + 7)
           pos += 7
           if (LEFT_DIGITS.containsKey(part)) {
               output.add(LEFT_DIGITS.getOrDefault(part, -1))
           } else {
               return Pair(false, output.toList())
           }
       }
       part = candidate.slice(pos until pos + MID_SENTINEL.length)
       if (part == MID_SENTINEL) {
           pos += MID_SENTINEL.length
       } else {
           return Pair(false, output.toList())
       }
       for (i in 0 until 6) {
           part = candidate.slice(pos until pos + 7)
           pos += 7
           if (RIGHT_DIGITS.containsKey(part)) {
               output.add(RIGHT_DIGITS.getOrDefault(part, -1))
           } else {
               return Pair(false, output.toList())
           }
       }
       part = candidate.slice(pos until pos + END_SENTINEL.length)
       if (part == END_SENTINEL) {
           pos += END_SENTINEL.length
       } else {
           return Pair(false, output.toList())
       }
       val sum = output.mapIndexed { i, v -> if (i % 2 == 0) v * 3 else v }.sum()
       return Pair(sum % 10 == 0, output.toList())
   }
   val candidate = input.trim()
   var out = decode(candidate)
   if (out.first) {
       println(out.second)
   } else {
       out = decode(candidate.reversed())
       if (out.first) {
           print(out.second)
           println(" Upside down")
       } else {
           if (out.second.size == 12) {
               println("Invalid checksum")
           } else {
               println("Invalid digit(s)")
           }
       }
   }

}

fun main() {

   val barcodes = listOf(
       "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
       "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
       "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
       "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
       "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
       "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
       "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
       "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
       "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
       "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ",
   )
   for (barcode in barcodes) {
       decodeUPC(barcode)
   }

}</lang>

Output:
[9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9]
[4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0]
[8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside down
[9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside down
Invalid digit(s)
[3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside down
[2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8]
[8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside down
[7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0]
[6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5]

Nim

Translation of: D

<lang Nim>import algorithm, sequtils, strutils

const

 LeftDigits = ["   ## #",
               "  ##  #",
               "  #  ##",
               " #### #",
               " #   ##",
               " ##   #",
               " # ####",
               " ### ##",
               " ## ###",
               "   # ##"]
 RightDigits = LeftDigits.mapIt(it.multiReplace(("#", " "), (" ", "#")))
 EndSentinel = "# #"
 MidSentinel = " # # "


template isEven(n: int): bool = (n and 1) == 0


proc decodeUPC(input: string) =

 #.................................................................................................
 proc decode(candidate: string): tuple[valid: bool, list: seq[int]] =
   const Invalid = (false, @[])
   var pos = 0
   var next = pos + EndSentinel.len
   if candidate[pos..<next] == EndSentinel:
     pos = next
   else:
     return Invalid
   for _ in 1..6:
     next = pos + 7
     let i = LeftDigits.find(candidate[pos..<next])
     if i >= 0:
       result.list.add i
       pos = next
     else:
       return Invalid
   next = pos + MidSentinel.len
   if candidate[pos..<next] == MidSentinel:
     pos = next
   else:
     return Invalid
   for _ in 1..6:
     next = pos + 7
     let i = RightDigits.find(candidate[pos..<next])
     if i >= 0:
       result.list.add i
       pos = next
     else:
       return Invalid
   next = pos + EndSentinel.len
   if candidate[pos..<next] == EndSentinel:
     pos = next
   else:
     return Invalid
   var sum = 0
   for i, v in result.list:
     sum += (if i.isEven: 3 * v else: v)
   result.valid = sum mod 10 == 0
 #.................................................................................................
 var candidate = input.strip()
 let output = candidate.decode()
 if output.valid:
   echo output.list.join(", ")
 else:
   candidate.reverse()
   let output = candidate.decode()
   if output.valid:
     echo output.list.join(", "), " Upside down"
   elif output.list.len == 0:
     echo "Invalid digit(s)"
   else:
     echo "Invalid checksum: ", output.list.join(", ")


  1. ———————————————————————————————————————————————————————————————————————————————————————————————————

when isMainModule:

 const BarCodes = [
   "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
   "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
   "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
   "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
   "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
   "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
   "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
   "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
   "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
   "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ",
   ]
 for barcode in BarCodes:
   barcode.decodeUPC()</lang>
Output:
9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9
4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0
8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6 Upside down
9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1 Upside down
Invalid digit(s)
3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7 Upside down
2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8
8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3 Upside down
7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0
6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5

Perl

Translation of: Raku

<lang perl>use strict; use warnings; use feature 'say';

sub decode_UPC {

   my($line) = @_;
   my(%pattern_to_digit_1,%pattern_to_digit_2,@patterns1,@patterns2,@digits,$sum);
   for my $p ('   ## #', '  ##  #', '  #  ##', ' #### #', ' #   ##', ' ##   #', ' # ####', ' ### ##', ' ## ###', '   # ##') {
       push @patterns1, $p;
       push @patterns2, $p =~ tr/# / #/r;
   }
   $pattern_to_digit_1{$patterns1[$_]} = $_ for 0..$#patterns1;
   $pattern_to_digit_2{$patterns2[$_]} = $_ for 0..$#patterns2;
    my $re = '\s*# #\s*' .
             "(?<match1>(?:@{[join '|', @patterns1]}){6})" .
             '\s*# #\s*' .
             "(?<match2>(?:@{[join '|', @patterns2]}){6})" .
             '\s*# #\s*';
    $line =~ /^$re$/g || return;
   my($match1,$match2) = ($+{match1}, $+{match2});
   push @digits, $pattern_to_digit_1{$_} for $match1 =~ /(.{7})/g;
   push @digits, $pattern_to_digit_2{$_} for $match2 =~ /(.{7})/g;
   $sum += (3,1)[$_%2] * $digits[$_] for 0..11;
   $sum % 10 ?  : join , @digits;

}

my @lines = (

   '         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ',
    '        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #      ',
   '         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #       ',
     '       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ',
   '         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #       ',
  '          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #    ',
   '         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #     ',
    '        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #      ',
   '         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ',
    '        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #      ',

);

for my $line (@lines) {

   say decode_UPC($line)
    // decode_UPC(join , reverse split , $line)
    // 'Invalid';

} </lang>

Output:
924773271019
403944441050
834999676706
939825158811
Invalid
316313718717
214575875608
818778841813
706466743030
653483540435

Phix

<lang Phix>constant numbers = {" ## #", -- 0

                   "  ##  #", -- 1
                   "  #  ##", -- 2
                   " #### #", -- 3
                   " #   ##", -- 4
                   " ##   #", -- 5
                   " # ####", -- 6
                   " ### ##", -- 7
                   " ## ###", -- 8
                   "   # ##"} -- 9

procedure decode(string bar_code)

   bar_code = trim(bar_code)
   if length(bar_code)=95
   and bar_code[1..3]="# #"
   and bar_code[46..50]=" # # "
   and bar_code[93..95]="# #" then
       for reversed=false to true do
           sequence r = {}
           for i=1 to 12 do
               integer st = iff(i<=6?i*7-3:i*7+2)
               string number = bar_code[st..st+6]
               if i>6 then number = substitute_all(number," #X","X #") end if
               r &= find(number,numbers)-1
           end for
           if not find(-1,r) then
               if remainder(sum(sq_mul(r,{3,1,3,1,3,1,3,1,3,1,3,1})),10) then
                   printf(1,"invalid checksum\n")
               else
                   printf(1,"%v%s\n",{r,iff(reversed?" (upside down)","")})
               end if
               return
           end if
           bar_code = reverse(bar_code)
       end for
   end if
   printf(1,"invalid\n")

end procedure

constant bar_codes = split("""

        # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       
       # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         
        # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         
      # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        
        # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          
         # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         
        # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        
       # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         
        # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       
       # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         

""","\n",true) for i=1 to length(bar_codes) do

   decode(bar_codes[i])

end for</lang>

Output:
{9,2,4,7,7,3,2,7,1,0,1,9}
{4,0,3,9,4,4,4,4,1,0,5,0}
{8,3,4,9,9,9,6,7,6,7,0,6} (upside down)
{9,3,9,8,2,5,1,5,8,8,1,1} (upside down)
invalid
{3,1,6,3,1,3,7,1,8,7,1,7} (upside down)
{2,1,4,5,7,5,8,7,5,6,0,8}
{8,1,8,7,7,8,8,4,1,8,1,3} (upside down)
{7,0,6,4,6,6,7,4,3,0,3,0}
{6,5,3,4,8,3,5,4,0,4,3,5}

PicoLisp

<lang PicoLisp>(de l2n (Lst)

  (case Lst
     ((0 0 0 1 1 0 1) 0)
     ((0 0 1 1 0 0 1) 1)
     ((0 0 1 0 0 1 1) 2)
     ((0 1 1 1 1 0 1) 3)
     ((0 1 0 0 0 1 1) 4)
     ((0 1 1 0 0 0 1) 5)
     ((0 1 0 1 1 1 1) 6)
     ((0 1 1 1 0 1 1) 7)
     ((0 1 1 0 1 1 1) 8)
     ((0 0 0 1 0 1 1) 9) ) )

(de convs (Lst Flg)

  (make
     (for L Lst
        (link
           (if2 (= "#" L) Flg 0 1 1 0) ) ) ) )

(de getL (Lst)

  (make
     (cut 3 'Lst)
     (do 6
        (link (convs (cut 7 'Lst))) )
     (cut 5 'Lst)
     (do 6
        (link (convs (cut 7 'Lst) T)) ) ) )

(de parse (Str)

  (let Lst
     (make
        (link (clip (chop Str)))
        (link (reverse (car (made)))) )
     (find
        '((N) (fully num? N))
        (mapcar '((L) (mapcar l2n (getL L))) Lst) ) ) )

(de upc (Str)

  (let Lst (parse Str)
     (cons
        Lst
        (%
           (apply + (mapcar * Lst (circ 3 1)))
           10 ) ) ) )

(setq *U

  (quote
     "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       "
     "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         "
     "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         "
     "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        "
     "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          "
     "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         "
     "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        "
     "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         "
     "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       "
     "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         " ) )

(for L (mapcar upc *U)

  (println (if (car L) @ 'invalid)) )</lang>
Output:
(9 2 4 7 7 3 2 7 1 0 1 9)
(4 0 3 9 4 4 4 4 1 0 5 0)
(8 3 4 9 9 9 6 7 6 7 0 6)
(9 3 9 8 2 5 1 5 8 8 1 1)
invalid
(3 1 6 3 1 3 7 1 8 7 1 7)
(2 1 4 5 7 5 8 7 5 6 0 8)
(8 1 8 7 7 8 8 4 1 8 1 3)
(7 0 6 4 6 6 7 4 3 0 3 0)
(6 5 3 4 8 3 5 4 0 4 3 5)

Python

<lang python>"""UPC-A barcode reader. Requires Python =>3.6""" import itertools import re

RE_BARCODE = re.compile(

   r"^(?P<s_quiet> +)"  # quiet zone
   r"(?P<s_guard># #)"  # start guard
   r"(?P<left>[ #]{42})"  # left digits
   r"(?P<m_guard> # # )"  # middle guard
   r"(?P<right>[ #]{42})"  # right digits
   r"(?P<e_guard># #)"  # end guard
   r"(?P<e_quiet> +)$"  # quiet zone

)

LEFT_DIGITS = {

   (0, 0, 0, 1, 1, 0, 1): 0,
   (0, 0, 1, 1, 0, 0, 1): 1,
   (0, 0, 1, 0, 0, 1, 1): 2,
   (0, 1, 1, 1, 1, 0, 1): 3,
   (0, 1, 0, 0, 0, 1, 1): 4,
   (0, 1, 1, 0, 0, 0, 1): 5,
   (0, 1, 0, 1, 1, 1, 1): 6,
   (0, 1, 1, 1, 0, 1, 1): 7,
   (0, 1, 1, 0, 1, 1, 1): 8,
   (0, 0, 0, 1, 0, 1, 1): 9,

}

RIGHT_DIGITS = {

   (1, 1, 1, 0, 0, 1, 0): 0,
   (1, 1, 0, 0, 1, 1, 0): 1,
   (1, 1, 0, 1, 1, 0, 0): 2,
   (1, 0, 0, 0, 0, 1, 0): 3,
   (1, 0, 1, 1, 1, 0, 0): 4,
   (1, 0, 0, 1, 1, 1, 0): 5,
   (1, 0, 1, 0, 0, 0, 0): 6,
   (1, 0, 0, 0, 1, 0, 0): 7,
   (1, 0, 0, 1, 0, 0, 0): 8,
   (1, 1, 1, 0, 1, 0, 0): 9,

}


MODULES = {

   " ": 0,
   "#": 1,

}

DIGITS_PER_SIDE = 6 MODULES_PER_DIGIT = 7


class ParityError(Exception):

   """Exception raised when a parity error is found."""


class ChecksumError(Exception):

   """Exception raised when check digit does not match."""


def group(iterable, n):

   """Chunk the iterable into groups of size ``n``."""
   args = [iter(iterable)] * n
   return tuple(itertools.zip_longest(*args))


def parse(barcode):

   """Return the 12 digits represented by the given barcode. Raises a
   ParityError if any digit fails the parity check."""
   match = RE_BARCODE.match(barcode)
   # Translate bars and spaces to 1s and 0s so we can do arithmetic
   # with them. Group "modules" into chunks of 7 as we go.
   left = group((MODULES[c] for c in match.group("left")), MODULES_PER_DIGIT)
   right = group((MODULES[c] for c in match.group("right")), MODULES_PER_DIGIT)
   # Parity check
   left, right = check_parity(left, right)
   # Lookup digits
   return tuple(
       itertools.chain(
           (LEFT_DIGITS[d] for d in left),
           (RIGHT_DIGITS[d] for d in right),
       )
   )


def check_parity(left, right):

   """Check left and right parity. Flip left and right if the barcode
   was scanned upside down."""
   # When reading from left to right, each digit on the left should
   # have odd parity, and each digit on the right should have even
   # parity.
   left_parity = sum(sum(d) % 2 for d in left)
   right_parity = sum(sum(d) % 2 for d in right)
   # Use left and right parity to check if the barcode was scanned
   # upside down. Flip it if it was.
   if left_parity == 0 and right_parity == DIGITS_PER_SIDE:
       _left = tuple(tuple(reversed(d)) for d in reversed(right))
       right = tuple(tuple(reversed(d)) for d in reversed(left))
       left = _left
   elif left_parity != DIGITS_PER_SIDE or right_parity != 0:
       # Error condition. Mixed parity.
       error = tuple(
           itertools.chain(
               (LEFT_DIGITS.get(d, "_") for d in left),
               (RIGHT_DIGITS.get(d, "_") for d in right),
           )
       )
       raise ParityError(" ".join(str(d) for d in error))
   return left, right


def checksum(digits):

   """Return the check digit for the given digits. Raises a
   ChecksumError if the check digit does not match."""
   odds = (digits[i] for i in range(0, 11, 2))
   evens = (digits[i] for i in range(1, 10, 2))
   check_digit = (sum(odds) * 3 + sum(evens)) % 10
   if check_digit != 0:
       check_digit = 10 - check_digit
   if digits[-1] != check_digit:
       raise ChecksumError(str(check_digit))
   return check_digit


def main():

   barcodes = [
       "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
       "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
       "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
       "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
       "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
       "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
       "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
       "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
       "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
       "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ",
       "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  ## ##  #  ### # #         ",
   ]
   for barcode in barcodes:
       try:
           digits = parse(barcode)
       except ParityError as err:
           print(f"{err} parity error!")
           continue
       try:
           check_digit = checksum(digits)
       except ChecksumError as err:
           print(f"{' '.join(str(d) for d in digits)} checksum error! ({err})")
           continue
       print(f"{' '.join(str(d) for d in digits)}")


if __name__ == "__main__":

   main()

</lang>

Output:
$ python barcode.py 
9 2 4 7 7 3 2 7 1 0 1 9
4 0 3 9 4 4 4 4 1 0 5 0
8 3 4 9 9 9 6 7 6 7 0 6
9 3 9 8 2 5 1 5 8 8 1 1
7 4 8 1 5 9 9 2 3 9 2 _ parity error!
3 1 6 3 1 3 7 1 8 7 1 7
2 1 4 5 7 5 8 7 5 6 0 8
8 1 8 7 7 8 8 4 1 8 1 3
7 0 6 4 6 6 7 4 3 0 3 0
6 5 3 4 8 3 5 4 0 4 3 5
6 5 3 4 8 3 5 4 0 4 2 5 checksum error! (8)

Racket

<lang racket>#lang racket

inspired by Kotlin

(define (is-#? c) (char=? c #\#))

(define left-digits

 (for/hash ((i (in-naturals))
            (c '((#f #f #t #t #f)
                 (#f #t #t #f #f)
                 (#f #t #f #f #t)
                 (#t #t #t #t #f)
                 (#t #f #f #f #t)
                 (#t #t #f #f #f)
                 (#t #f #t #t #t)
                 (#t #t #t #f #t)
                 (#t #t #f #t #t)
                 (#f #f #t #f #t))))
   (values `(#f ,@c #t) i)))

(define right-digits (for/hash (([k v] left-digits)) (values (map not k) v)))

(define (lookup-blocks bits hsh fail)

 (let recur ((bs bits) (r null))
   (if (null? bs)
       (reverse r)
       (let-values (((bs′ tl) (split-at bs 7)))
         (let ((d (hash-ref hsh bs′ (λ () (fail (list 'not-found bs′))))))
           (recur tl (cons d r)))))))

(define (extract-blocks b fail)

 (let*-values
     (((e-l-m-r-e) (map is-#? (string->list (string-trim b))))
      ((_) (unless (= (length e-l-m-r-e) (+ 3 (* 7 6) 5 (* 7 6) 3))
             (fail 'wrong-length)))
      ((e l-m-r-e) (split-at e-l-m-r-e 3))
      ((_) (unless (equal? e '(#t #f #t)) (fail 'left-sentinel)))
      ((l-m-r e) (split-at-right l-m-r-e 3))
      ((_) (unless (equal? e '(#t #f #t)) (fail 'right-sentinel)))
      ((l m-r) (split-at l-m-r 42))
      ((m r) (split-at m-r 5))
      ((_) (unless (equal? m '(#f #t #f #t #f)) (fail 'mid-sentinel))))
   (values l r)))

(define (upc-checksum? ds)

 (zero? (modulo (for/sum ((m (in-cycle '(3 1))) (d ds)) (* m d)) 10)))

(define (lookup-digits l r fail (transform values))

 (let/ec fail-lookups
   (define ds (append (lookup-blocks l left-digits (λ _ (fail-lookups #f)))
                      (lookup-blocks r right-digits (λ _ (fail-lookups #f)))))
   (if (upc-checksum? ds)
       (transform ds)
       (fail (list 'checksum (transform ds))))))

(define (decode-upc barcode upside-down fail)

 (define-values (l r) (extract-blocks barcode fail))
 (or (lookup-digits l r fail)
     (lookup-digits (reverse r) (reverse l) fail upside-down)))

(define (report-upc barcode)

 (displayln (decode-upc barcode
                        (λ (v) (cons 'upside-down v))
                        (λ (e) (format "invalid: ~s" e)))))

(define (UPC)

 (for-each report-upc
           '("         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       "
             "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         "
             "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         "
             "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        "
             "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          "
             "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         "
             "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        "
             "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         "
             "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       "
             "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         "
             ; first element again, with corrupted second digit
             "         # #   # ##   # ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ")))

(module+ main (UPC))</lang>

Output:
(9 2 4 7 7 3 2 7 1 0 1 9)
(4 0 3 9 4 4 4 4 1 0 5 0)
(upside-down 8 3 4 9 9 9 6 7 6 7 0 6)
(upside-down 9 3 9 8 2 5 1 5 8 8 1 1)
#f
(upside-down 3 1 6 3 1 3 7 1 8 7 1 7)
(2 1 4 5 7 5 8 7 5 6 0 8)
(upside-down 8 1 8 7 7 8 8 4 1 8 1 3)
(7 0 6 4 6 6 7 4 3 0 3 0)
(6 5 3 4 8 3 5 4 0 4 3 5)
invalid: (checksum (9 9 4 7 7 3 2 7 1 0 1 9))

Raku

(formerly Perl 6) <lang perl6>sub decode_UPC ( Str $line ) {

   constant @patterns1 = '   ## #', '  ##  #', '  #  ##', ' #### #', ' #   ##',
                         ' ##   #', ' # ####', ' ### ##', ' ## ###', '   # ##';
   constant @patterns2 = @patterns1».trans( '#' => ' ', ' ' => '#' );
   constant %pattern_to_digit_1 = @patterns1.antipairs;
   constant %pattern_to_digit_2 = @patterns2.antipairs;
   constant $re = / ^  '# #'  (@patterns1) ** 6
                      ' # # ' (@patterns2) ** 6
                       '# #'                     $ /;
   $line.trim ~~ $re
       orelse return;
   my @digits = flat %pattern_to_digit_1{ $0».Str },
                     %pattern_to_digit_2{ $1».Str };
   return unless ( @digits Z* ( |(3,1) xx * ) ).sum %% 10;
   return @digits.join;

}

my @lines =

   '         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ',
    '        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #      ',
   '         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #       ',
     '       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ',
   '         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #       ',
  '          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #    ',
   '         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #     ',
    '        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #      ',
   '         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ',
    '        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #      ',

for @lines -> $line {

   say decode_UPC($line)
    // decode_UPC($line.flip)
    // 'Invalid';

}</lang>

Output:
924773271019
403944441050
834999676706
939825158811
Invalid
316313718717
214575875608
818778841813
706466743030
653483540435

REXX

<lang rexx>/*REXX program to read/interpret UPC symbols and translate them to a numberic string.*/

          #.0= '   ## #'
          #.1= '  ##  #'
          #.2= '  #  ##'
          #.3= ' #### #'
          #.4= ' #   ##'
          #.5= ' ##   #'
          #.6= ' # ####'
          #.7= ' ### ##'
          #.8= ' ## ###'                                /* [↓]  right─sided UPC digits.*/
          #.9= '   # ##' ;        do i=0  for 10;     ##.i= translate(#.i, ' #', "# ")
                                  end  /*i*/

say center('UPC', 14, "─") ' ---'copies(1234567, 6)"-----"copies(1234567, 6)'---' @.=. @.1 = ' # # # ## # ## # ## ### ## ### ## #### # # # ## ## # # ## ## ### # ## ## ### # # # ' @.2 = ' # # # ## ## # #### # # ## # ## # ## # # # ### # ### ## ## ### # # ### ### # # # ' @.3 = ' # # # # # ### # # # # # # # # # # ## # ## # ## # ## # # #### ### ## # # ' @.4 = ' # # ## ## ## ## # # # # ### # ## ## # # # ## ## # ### ## ## # # #### ## # # # ' @.5 = ' # # ### ## # ## ## ### ## # ## # # ## # # ### # ## ## # # ### # ## ## # # # ' @.6 = ' # # # # ## ## # # # # ## ## # # # # # #### # ## # #### #### # # ## # #### # # ' @.7 = ' # # # ## ## # # ## ## # ### ## ## # # # # # # # # ### # # ### # # # # # ' @.8 = ' # # # # ## ## # # ## ## ### # # # # # ### ## ## ### ## ### ### ## # ## ### ## # # ' @.9 = ' # # ### ## ## # # #### # ## # #### # #### # # # # # ### # # ### # # # ### # # # ' @.10= ' # # # #### ## # #### # # ## ## ### #### # # # # ### # ### ### # # ### # # # ### # '

         ends= '# #'                                        /*define ENDS literal const*/
  do j=1  while @.j\==.;        $= @.j
  txt=                                                      /*initialize  TXT  variable*/
  if left($, 9)\=     | right($, 9)\=      then txt= 'bad blanks'
  $= strip($);   $$= $                                      /*elide blanks at ends of $*/
  L= length($)                                              /*obtain length of $ string*/
  if left($, 3) \==ends | right($, 3) \==ends  then txt= 'bad fence'
  if L \== 95           & txt==              then txt= 'bad length'
  $= substr($, 4, L - length(ends)*2)                                  /*elide "ends". */
  $= delstr($, length($) % 2 - 1,  5)                                  /*  "   middle. */
  sum= 0                                                               /*initialize SUM*/
  if txt==  then do k=1  for 12;     parse var  $   x  +7  $         /*get UPC digit.*/
                      do d=0  for 10;  if x==#.d | x==##.d  then leave /*valid digit?  */
                      end   /*d*/
                   if d==10 & k \==12  then do;   txt= 'reversed' ;   leave;   end
                   if d==10            then do;   txt= 'bad digit';   leave;   end
                   if k // 2  then sum= sum +    d * 3                 /*mult. by  3.  */
                              else sum= sum +    d                     /*  "    "  1.  */
                   txt= txt  ||  d
                   end     /*k*/
  if left(txt,1)\=="b"  then if sum//10\==0  then txt= 'bad checksum'  /*invalid sum?  */
  say center( strip(txt), 15)  ' '   $$         /*show chksum (or err msg) with the UPC*/
  end   /*j*/                                   /*stick a fork in it,  we're all done. */</lang>
output   when using the internal default input:
─────UPC──────    ---123456712345671234567123456712345671234567-----123456712345671234567123456712345671234567---
 924773271019     # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #
 403944441050     # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #
   reversed       # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #
   reversed       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #
   bad digit      # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #
   reversed       # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #
 214575875608     # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #
   reversed       # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #
 706466743030     # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #
  bad length      # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### #

Ruby

Translation of: C

<lang ruby>DIGIT_F = {

   "   ## #" => 0,
   "  ##  #" => 1,
   "  #  ##" => 2,
   " #### #" => 3,
   " #   ##" => 4,
   " ##   #" => 5,
   " # ####" => 6,
   " ### ##" => 7,
   " ## ###" => 8,
   "   # ##" => 9,

}

DIGIT_R = {

   "###  # " => 0,
   "##  ## " => 1,
   "## ##  " => 2,
   "#    # " => 3,
   "# ###  " => 4,
   "#  ### " => 5,
   "# #    " => 6,
   "#   #  " => 7,
   "#  #   " => 8,
   "### #  " => 9,

}

END_SENTINEL = "# #" MID_SENTINEL = " # # "

def decode_upc(s)

   def decode_upc_impl(input)
       upc = input.strip
       if upc.length != 95 then
           return false
       end
       pos = 0
       digits = []
       sum = 0
       # end sentinel
       if upc[pos .. pos + 2] == END_SENTINEL then
           pos += 3
       else
           return false
       end
       # 6 left hand digits
       for i in 0 .. 5
           digit = DIGIT_F[upc[pos .. pos + 6]]
           if digit == nil then
               return false
           else
               digits.push(digit)
               sum += digit * [1, 3][digits.length % 2]
               pos += 7
           end
       end
       # mid sentinel
       if upc[pos .. pos + 4] == MID_SENTINEL then
           pos += 5
       else
           return false
       end
       # 6 right hand digits
       for i in 0 .. 5
           digit = DIGIT_R[upc[pos .. pos + 6]]
           if digit == nil then
               return false
           else
               digits.push(digit)
               sum += digit * [1, 3][digits.length % 2]
               pos += 7
           end
       end
       # end sentinel
       if upc[pos .. pos + 2] == END_SENTINEL then
           pos += 3
       else
           return false
       end
       if sum % 10  == 0 then
           print digits, " "
           return true
       else
           print "Failed Checksum "
           return false
       end
   end
   if decode_upc_impl(s) then
       puts "Rightside Up"
   elsif decode_upc_impl(s.reverse) then
       puts "Upside Down"
   else
       puts "Invalid digit(s)"
   end

end

def main

   num = 0
   print "%2d: " % [num += 1]
   decode_upc("         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ")
   print "%2d: " % [num += 1]
   decode_upc("        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ")
   print "%2d: " % [num += 1]
   decode_upc("         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ")
   print "%2d: " % [num += 1]
   decode_upc("       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ")
   print "%2d: " % [num += 1]
   decode_upc("         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ")
   print "%2d: " % [num += 1]
   decode_upc("          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ")
   print "%2d: " % [num += 1]
   decode_upc("         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ")
   print "%2d: " % [num += 1]
   decode_upc("        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ")
   print "%2d: " % [num += 1]
   decode_upc("         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ")
   print "%2d: " % [num += 1]
   decode_upc("        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         ")

end

main()</lang>

Output:
 1: [9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9] Rightside Up
 2: [4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0] Rightside Up
 3: [8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside Down
 4: [9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside Down
 5: Invalid digit(s)
 6: [3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside Down
 7: [2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8] Rightside Up
 8: [8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside Down
 9: [7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0] Rightside Up
10: [6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5] Rightside Up

Wren

Translation of: Ruby
Library: Wren-fmt

<lang ecmascript>import "/fmt" for Fmt

var digitL = {

   "   ## #": 0,
   "  ##  #": 1,
   "  #  ##": 2,
   " #### #": 3,
   " #   ##": 4,
   " ##   #": 5,
   " # ####": 6,
   " ### ##": 7,
   " ## ###": 8,
   "   # ##": 9

}

var digitR = {

   "###  # ": 0,
   "##  ## ": 1,
   "## ##  ": 2,
   "#    # ": 3,
   "# ###  ": 4,
   "#  ### ": 5,
   "# #    ": 6,
   "#   #  ": 7,
   "#  #   ": 8,
   "### #  ": 9

}

var endSentinel = "# #" // also at start var midSentinel = " # # "

var decodeUpc = Fn.new { |s|

   var decodeUpcImpl = Fn.new { |input|
       var upc = input.trim()
       if (upc.count != 95) return false
       var pos = 0
       var digits = []
       var sum = 0
       var oneThree = [1, 3]
       // end sentinel
       if (upc[pos..pos+2] == endSentinel) {
           pos = pos + 3
       } else {
           return false
       }
       // 6 left hand digits
       for (i in 0..5) {
           var digit = digitL[upc[pos..pos+6]]
           if (!digit) return false
           digits.add(digit)
           sum = sum + digit * oneThree[digits.count % 2]
           pos = pos + 7
       }
       // mid sentinel
       if (upc[pos..pos+4] == midSentinel) {
           pos = pos + 5
       } else {
           return false
       }
       // 6 right hand digits
       for (i in 0..5) {
           var digit = digitR[upc[pos..pos+6]]
           if (!digit) return false
           digits.add(digit)
           sum = sum + digit * oneThree[digits.count % 2]
           pos = pos + 7
       }
       // end sentinel
       if (upc[pos..pos+2] != endSentinel) return false
       if (sum%10 == 0) {
           System.write("%(digits) ")
           return true
       }
       System.write("Failed Checksum ")
       return false
   }
   if (decodeUpcImpl.call(s)) {
       System.print("Rightside Up")
   } else if (decodeUpcImpl.call(s[-1..0])) {
       System.print("Upside Down")
   } else {
       System.print("Invalid digit(s)")
   }

}

var barcodes = [

   "         # #   # ##  #  ## #   ## ### ## ### ## #### # # # ## ##  #   #  ##  ## ###  # ##  ## ### #  # #       ",
   "        # # #   ##   ## # #### #   # ## #   ## #   ## # # # ###  # ###  ##  ## ###  # #  ### ###  # # #         ",
   "         # #    # # #  ###  #   #    # #  #   #    # # # # ## #   ## #   ## #   ##   # # #### ### ## # #         ",
   "       # # ##  ## ##  ##   #  #   #  # ###  # ##  ## # # #   ## ##  #  ### ## ## #   # #### ## #   # #        ",
   "         # # ### ## #   ## ## ###  ##  # ##   #   # ## # # ### #  ## ##  #    # ### #  ## ##  #      # #          ",
   "          # #  #   # ##  ##  #   #   #  # ##  ##  #   # # # # #### #  ##  # #### #### # #  ##  # #### # #         ",
   "         # #  #  ##  ##  # #   ## ##   # ### ## ##   # # # #  #   #   #  #  ### # #    ###  # #  #   # #        ",
   "        # # #    # ##  ##   #  # ##  ##  ### #   #  # # # ### ## ## ### ## ### ### ## #  ##  ### ## # #         ",
   "         # # ### ##   ## # # #### #   ## # #### # #### # # #   #  # ###  #    # ###  # #    # ###  # # #       ",
   "        # # # #### ##   # #### # #   ## ## ### #### # # # #  ### # ###  ###  # # ###  #    # #  ### # #         "

] var n = 0 for (barcode in barcodes) {

   n = n + 1
   Fmt.write("$2d: ", n)
   decodeUpc.call(barcode)

}</lang>

Output:
 1: [9, 2, 4, 7, 7, 3, 2, 7, 1, 0, 1, 9] Rightside Up
 2: [4, 0, 3, 9, 4, 4, 4, 4, 1, 0, 5, 0] Rightside Up
 3: [8, 3, 4, 9, 9, 9, 6, 7, 6, 7, 0, 6] Upside Down
 4: [9, 3, 9, 8, 2, 5, 1, 5, 8, 8, 1, 1] Upside Down
 5: Invalid digit(s)
 6: [3, 1, 6, 3, 1, 3, 7, 1, 8, 7, 1, 7] Upside Down
 7: [2, 1, 4, 5, 7, 5, 8, 7, 5, 6, 0, 8] Rightside Up
 8: [8, 1, 8, 7, 7, 8, 8, 4, 1, 8, 1, 3] Upside Down
 9: [7, 0, 6, 4, 6, 6, 7, 4, 3, 0, 3, 0] Rightside Up
10: [6, 5, 3, 4, 8, 3, 5, 4, 0, 4, 3, 5] Rightside Up

zkl

<lang zkl>var lhd=Dictionary(), rhd=Dictionary(); [0..].zip(List(

   "0 0 0 1 1 0 1", //--> "___##_#":0   "###__#_":0
   "0 0 1 1 0 0 1", 
   "0 0 1 0 0 1 1",
   "0 1 1 1 1 0 1",
   "0 1 0 0 0 1 1",
   "0 1 1 0 0 0 1",
   "0 1 0 1 1 1 1",
   "0 1 1 1 0 1 1",
   "0 1 1 0 1 1 1",
   "0 0 0 1 0 1 1") //--> "___#_##":9    "###_#__":9

).pump(Void,fcn([(n,bs)]){

  bs-=" ";
  lhd[bs.translate("01","_#")]=n;
  rhd[bs.translate("10","_#")]=n;

});

fcn parseBarCode(barcode, one=True){ // --> 12 digits

  upsideDown:='wrap{	// was I looking at this bar code upside down?
     if(one and (r:=parseBarCode(barcode.reverse(),False))) return(r);
     return(False);
  };
  var [const] start=RegExp(String("_"*9, "+#_#")), tail="_"*7;
  if(not start.search(barcode)) return(upsideDown());
  r,idx,d,mark := List(), start.matched[0][1], lhd, "_#_#_";
  do(2){
     do(6){

if(Void==(z:=d.find(barcode[idx,7]))) return(upsideDown()); r.append(z); idx+=7;

     }
     if(barcode[idx,5] != mark) return(Void);
     d,idx,mark = rhd, idx+5, "#_#__";
  }
  if(tail!=barcode[idx,7]) return(Void);  // 9 trailing blanks? two checked above
  r

}</lang> Or, if you like way too long regular expressions: <lang zkl>var upcRE = RegExp(String("_"*9, "+#_#", lhd.keys.concat("|","(",")")*6, "_#_#_", rhd.keys.concat("|","(",")")*6, "#_#", "_"*9)),

   digits=lhd.copy().extend(rhd);

fcn parseBarCode2(barcode){ // --> 12 digits

  if(not (upcRE.search(barcode) or upcRE.search(barcode.reverse()))) return(False);
  upcRE.matched[1,*] // ( (a,b), "_#_####","_##___#", 10 more digit patterns )
  .apply(digits.get)

}</lang> <lang zkl>barcodes:=

  1. <<<"

_________#_#___#_##__#__##_#___##_###_##_###_##_####_#_#_#_##_##__#___#__##__##_###__#_##__##_###_#__#_#_________ _________#_#_#___##___##_#_####_#___#_##_#___##_#___##_#_#_#_###__#_###__##__##_###__#_#__###_###__#_#_#_________ _________#_#____#_#_#__###__#___#____#_#__#___#____#_#_#_#_##_#___##_#___##_#___##___#_#_####_###_##_#_#_________ _________#_#_##__##_##__##___#__#___#__#_###__#_##__##_#_#_#___##_##__#__###_##_##_#___#_####_##_#___#_#_________ _________#_#_###_##_#___##_##_###__##__#_##___#___#_##_#_#_###_#__##_##__#____#_###_#__##_##__#______#_#__________ __________#_#__#___#_##__##__#___#___#__#_##__##__#___#_#_#_#_####_#__##__#_####_####_#_#__##__#_####_#_#____________ _________#_#__#__##__##__#_#___##_##___#_###_##_##___#_#_#_#__#___#___#__#__###_#_#____###__#_#__#___#_#_________ _________#_#_#____#_##__##___#__#_##__##__###_#___#__#_#_#_###_##_##_###_##_###_###_##_#__##__###_##_#_#__________ _________#_#_###_##___##_#_#_####_#___##_#_####_#_####_#_#_#___#__#_###__#____#_###__#_#____#_###__#_#_#_________ _______________#_#_#_####_##___#_####_#_#___##_##_###_####_#_#_#_#__###_#_###__###__#_#_###__#____#_#__###_#_#_________" .split("\n");

  1. <<<

foreach n,barcode in ([1..].zip(barcodes)){

  bc:=parseBarCode(barcode);
  println("%2d: [%s]".fmt(n,bc and bc.concat(" ") or "Not valid"));

}</lang>

Output:
 1: [9 2 4 7 7 3 2 7 1 0 1 9]
 2: [4 0 3 9 4 4 4 4 1 0 5 0]
 3: [8 3 4 9 9 9 6 7 6 7 0 6]
 4: [9 3 9 8 2 5 1 5 8 8 1 1]
 5: [Not valid]
 6: [3 1 6 3 1 3 7 1 8 7 1 7]
 7: [2 1 4 5 7 5 8 7 5 6 0 8]
 8: [8 1 8 7 7 8 8 4 1 8 1 3]
 9: [7 0 6 4 6 6 7 4 3 0 3 0]
10: [6 5 3 4 8 3 5 4 0 4 3 5]