Middle three digits
You are encouraged to solve this task according to the task description, using any language you may know.
The task is to:
- “Write a function/procedure/subroutine that is called with an integer value and returns the middle three digits of the integer if possible or a clear indication of an error if this is not possible.”
- Note: The order of the middle digits should be preserved.
Your function should be tested with the following values; the first line should return valid answers, those of the second line should return clear indications of an error:
123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345 1, 2, -1, -10, 2002, -2002, 0
Show your output on this page.
Ada
<lang Ada>with Ada.Text_IO;
procedure Middle_Three_Digits is
Impossible: exception;
function Middle_String(I: Integer; Middle_Size: Positive) return String is
S: constant String := Integer'Image(I);
First: Natural := S'First;
Full_Size, Border: Natural;
begin
while S(First) not in '0' .. '9' loop -- skip leading blanks and minus
First := First + 1;
end loop;
Full_Size := S'Last-First+1;
if (Full_Size < Middle_Size) or (Full_Size mod 2 = 0) then
raise Impossible;
else
Border := (Full_Size - Middle_Size)/2;
return S(First+Border .. First+Border+Middle_Size-1);
end if;
end Middle_String;
Inputs: array(Positive range <>) of Integer :=
(123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345,
1, 2, -1, -10, 2002, -2002, 0);
Error_Message: constant String := "number of digits must be >= 3 and odd";
package IIO is new Ada.Text_IO.Integer_IO(Integer);
begin
for I in Inputs'Range loop
IIO.Put(Inputs(I), Width => 9);
Ada.Text_IO.Put(": ");
begin
Ada.Text_IO.Put(Middle_String(Inputs(I), 3));
exception
when Impossible => Ada.Text_IO.Put("****" & Error_Message & "****");
end;
Ada.Text_IO.New_Line;
end loop;
end Middle_Three_Digits;</lang>
- Output:
123: 123
12345: 234
1234567: 345
987654321: 654
10001: 000
-10001: 000
-123: 123
-100: 100
100: 100
-12345: 234
1: ****number of digits must be >= 3 and odd****
2: ****number of digits must be >= 3 and odd****
-1: ****number of digits must be >= 3 and odd****
-10: ****number of digits must be >= 3 and odd****
2002: ****number of digits must be >= 3 and odd****
-2002: ****number of digits must be >= 3 and odd****
0: ****number of digits must be >= 3 and odd****
C++
<lang C++>
- include <iostream>
- include <sstream>
- include <string>
// @author Martin Ettl // @date 2013-02-04
/**
* Convert variables of type T to std::string * * * @param d --> digit of type T * * @return <-- the corresponding string value */
template <typename T> const std::string toString(const T &d) {
std::ostringstream result; result << d; return result.str();
}
/**
* Determine the middle n digits of the integer. If it is not possible to determine the * the middle n digits, an empty string is provided. * * @param iDigit --> The digit to test * @param n --> The number of digits inbetween * * @return <-- the middle three digits */
std::string strMiddleNDigits(int iDigit, const int &n) {
// is negative: --> convert to a positive number
if(iDigit<0)
{
iDigit*=-1;
}
// convert to string
std::string strNumber (toString(iDigit));
size_t len(strNumber.length());
if( (len < n) || (len % 2 == 0) )
{
return "";
}
size_t mid(len/2);
return strNumber.substr(mid-n/2, n);
}
/**
* Determine the middle three digits of the integer. If it is not possible to determine the * the middle three digits, an empty string is provided. * * @param iDigit --> The digit to test * * @return <-- the middle three digits */
std::string strMiddleThreeDigits(int iDigit) {
return strMiddleNDigits(iDigit,3);
}
int main() {
const int iPassing[] = {123, 12345, 1234567, 987654321, 10001, -10001,
-123, -100, 100, -12345
};
for(unsigned int ui = 0; ui < 10; ++ui)
{
std::cout << "strMiddleThreeDigits("<< iPassing[ui] <<"): "
<< strMiddleThreeDigits(iPassing[ui])<< "\n";
}
const int iFailing[] = {1, 2, -1, -10, 2002, -2002, 0};
for(unsigned int ui = 0; ui < 7; ++ui)
{
std::string strResult = strMiddleThreeDigits(iFailing[ui]);
std::cout << "strMiddleThreeDigits("<< iFailing[ui] <<"): "
<< (strResult.empty()?"Need odd and >= 3 digits":strResult)
<< "\n";
}
return 0;
} </lang>
- Output:
strMiddleThreeDigits(123): 123 strMiddleThreeDigits(12345): 234 strMiddleThreeDigits(1234567): 345 strMiddleThreeDigits(987654321): 654 strMiddleThreeDigits(10001): 000 strMiddleThreeDigits(-10001): 000 strMiddleThreeDigits(-123): 123 strMiddleThreeDigits(-100): 100 strMiddleThreeDigits(100): 100 strMiddleThreeDigits(-12345): 234 strMiddleThreeDigits(1): Need odd and >= 3 digits strMiddleThreeDigits(2): Need odd and >= 3 digits strMiddleThreeDigits(-1): Need odd and >= 3 digits strMiddleThreeDigits(-10): Need odd and >= 3 digits strMiddleThreeDigits(2002): Need odd and >= 3 digits strMiddleThreeDigits(-2002): Need odd and >= 3 digits strMiddleThreeDigits(0): Need odd and >= 3 digits
D
<lang d>import std.stdio, std.traits, std.conv;
string middleThreeDigits(T)(in T n) if (isIntegral!T) {
auto s = n < 0 ? n.text()[1 .. $] : n.text();
auto len = s.length;
if (len < 3 || len % 2 == 0)
return "Need odd and >= 3 digits";
auto mid = len / 2;
return s[mid - 1 .. mid + 2];
}
void main() {
immutable passing = [123, 12345, 1234567, 987654321, 10001, -10001,
-123, -100, 100, -12345, long.min, long.max];
foreach (n; passing)
writefln("middleThreeDigits(%s): %s", n, middleThreeDigits(n));
immutable failing = [1, 2, -1, -10, 2002, -2002, 0,int.min,int.max];
foreach (n; failing)
writefln("middleThreeDigits(%s): %s", n, middleThreeDigits(n));
}</lang>
- Output:
middleThreeDigits(123): 123 middleThreeDigits(12345): 234 middleThreeDigits(1234567): 345 middleThreeDigits(987654321): 654 middleThreeDigits(10001): 000 middleThreeDigits(-10001): 000 middleThreeDigits(-123): 123 middleThreeDigits(-100): 100 middleThreeDigits(100): 100 middleThreeDigits(-12345): 234 middleThreeDigits(-9223372036854775808): 368 middleThreeDigits(9223372036854775807): 368 middleThreeDigits(1): Need odd and >= 3 digits middleThreeDigits(2): Need odd and >= 3 digits middleThreeDigits(-1): Need odd and >= 3 digits middleThreeDigits(-10): Need odd and >= 3 digits middleThreeDigits(2002): Need odd and >= 3 digits middleThreeDigits(-2002): Need odd and >= 3 digits middleThreeDigits(0): Need odd and >= 3 digits middleThreeDigits(-2147483648): Need odd and >= 3 digits middleThreeDigits(2147483647): Need odd and >= 3 digits
Alternative Version
This longer version gives a stronger typed output, and it tries to be faster avoiding conversions to string. <lang d>import std.stdio, std.traits, std.math, std.variant;
/// Returns a string with the error, or the three digits. Algebraic!(string, char[3]) middleThreeDigits(T)(in T n) if (isIntegral!T) {
// Awkward code to face abs(T.min) when T is signed.
ulong ln;
static if (isSigned!T) {
if (n >= 0) {
ln = n;
} else {
if (n == T.min) {
ln = -(n + 1);
ln++;
} else {
ln = -n;
}
}
} else {
ln = n;
}
if (ln < 100)
return typeof(return)("n is too short.");
immutable uint digits = 1 + cast(uint)log10(ln);
if (digits % 2 == 0)
return typeof(return)("n must have an odd number of digits.");
// From the Reddit answer by "millstone".
int drop = (digits - 3) / 2;
while (drop-- > 0)
ln /= 10;
char[3] result = void; result[2] = ln % 10 + '0'; ln /= 10; result[1] = ln % 10 + '0'; ln /= 10; result[0] = ln % 10 + '0'; return typeof(return)(result);
}
void main() {
immutable passing = [123, 12345, 1234567, 987654321, 10001,
-10001, -123, -100, 100, -12345, -8765432];
foreach (n; passing) {
auto mtd = middleThreeDigits(n);
// A string result means it didn't pass.
assert(!mtd.peek!string);
writefln("middleThreeDigits(%d): %s", n, mtd);
}
writeln();
immutable failing = [1, 2, -1, -10, 2002, -2002, 0,
15, int.min, int.max];
foreach (n; failing) {
auto mtd = middleThreeDigits(n);
assert(mtd.peek!string);
writefln("middleThreeDigits(%d): %s", n, mtd);
}
writeln();
immutable long[] passingL = [123, 12345, 1234567, 987654321, 10001,
-10001, -123, -100, 100, -12345,
-8765432, long.min, long.max];
foreach (n; passingL) {
auto mtd = middleThreeDigits(n);
assert(!mtd.peek!string);
writefln("middleThreeDigits(%d): %s", n, mtd);
}
writeln();
immutable long[] failingL = [1, 2, -1, -10, 2002, -2002, 0, 15];
foreach (n; failingL) {
auto mtd = middleThreeDigits(n);
assert(mtd.peek!string);
writefln("middleThreeDigits(%d): %s", n, mtd);
}
writeln();
{
immutable n = short.min;
auto mtd = middleThreeDigits(n);
assert(!mtd.peek!string);
writefln("middleThreeDigits(cast(short)%d): %s", n, mtd);
}
}</lang>
- Output:
middleThreeDigits(123): 123 middleThreeDigits(12345): 234 middleThreeDigits(1234567): 345 middleThreeDigits(987654321): 654 middleThreeDigits(10001): 000 middleThreeDigits(-10001): 000 middleThreeDigits(-123): 123 middleThreeDigits(-100): 100 middleThreeDigits(100): 100 middleThreeDigits(-12345): 234 middleThreeDigits(-8765432): 654 middleThreeDigits(1): n is too short. middleThreeDigits(2): n is too short. middleThreeDigits(-1): n is too short. middleThreeDigits(-10): n is too short. middleThreeDigits(2002): n must have an odd number of digits. middleThreeDigits(-2002): n must have an odd number of digits. middleThreeDigits(0): n is too short. middleThreeDigits(15): n is too short. middleThreeDigits(-2147483648): n must have an odd number of digits. middleThreeDigits(2147483647): n must have an odd number of digits. middleThreeDigits(123): 123 middleThreeDigits(12345): 234 middleThreeDigits(1234567): 345 middleThreeDigits(987654321): 654 middleThreeDigits(10001): 000 middleThreeDigits(-10001): 000 middleThreeDigits(-123): 123 middleThreeDigits(-100): 100 middleThreeDigits(100): 100 middleThreeDigits(-12345): 234 middleThreeDigits(-8765432): 654 middleThreeDigits(-9223372036854775808): 368 middleThreeDigits(9223372036854775807): 368 middleThreeDigits(1): n is too short. middleThreeDigits(2): n is too short. middleThreeDigits(-1): n is too short. middleThreeDigits(-10): n is too short. middleThreeDigits(2002): n must have an odd number of digits. middleThreeDigits(-2002): n must have an odd number of digits. middleThreeDigits(0): n is too short. middleThreeDigits(15): n is too short. middleThreeDigits(cast(short)-32768): 276
J
Solution: <lang j>asString=: ":"0 NB. convert vals to strings getPfxSize=: [: -:@| 3 -~ # NB. get size of prefix to drop before the 3 middle digits getMid3=: (3 {. getPfxSize }. ,&'err') :: ('err'"_) NB. get 3 middle digits or return 'err' getMiddle3=: getMid3@asString@:|</lang> Example: <lang j> vals=: 123 12345 1234567 987654321 10001 _10001 _123 _100 100 _12345 1 2 _1 _10 2002 _2002 0
getMiddle3 vals
123 234 345 654 000 000 123 100 100 234 err err err err err err err</lang>
Java
<lang Java>public class MiddleThreeDigits {
public static void main(String[] args) {
final long[] passing = {123, 12345, 1234567, 987654321, 10001, -10001,
-123, -100, 100, -12345, Long.MIN_VALUE, Long.MAX_VALUE};
final int[] failing = {1, 2, -1, -10, 2002, -2002, 0, Integer.MIN_VALUE,
Integer.MAX_VALUE};
for (long n : passing)
System.out.printf("middleThreeDigits(%s): %s\n", n, middleThreeDigits(n));
for (int n : failing)
System.out.printf("middleThreeDigits(%s): %s\n", n, middleThreeDigits(n));
}
public static <T> String middleThreeDigits(T n) {
String s = String.valueOf(n);
if (s.charAt(0) == '-')
s = s.substring(1);
int len = s.length();
if (len < 3 || len % 2 == 0)
return "Need odd and >= 3 digits";
int mid = len / 2;
return s.substring(mid - 1, mid + 2);
}
}</lang>
middleThreeDigits(123): 123 middleThreeDigits(12345): 234 middleThreeDigits(1234567): 345 middleThreeDigits(987654321): 654 middleThreeDigits(10001): 000 middleThreeDigits(-10001): 000 middleThreeDigits(-123): 123 middleThreeDigits(-100): 100 middleThreeDigits(100): 100 middleThreeDigits(-12345): 234 middleThreeDigits(-9223372036854775808): 368 middleThreeDigits(9223372036854775807): 368 middleThreeDigits(1): Need odd and >= 3 digits middleThreeDigits(2): Need odd and >= 3 digits middleThreeDigits(-1): Need odd and >= 3 digits middleThreeDigits(-10): Need odd and >= 3 digits middleThreeDigits(2002): Need odd and >= 3 digits middleThreeDigits(-2002): Need odd and >= 3 digits middleThreeDigits(0): Need odd and >= 3 digits middleThreeDigits(-2147483648): Need odd and >= 3 digits middleThreeDigits(2147483647): Need odd and >= 3 digits
NetRexx
<lang NetRexx>/* NetRexx */ options replace format comments java crossref symbols nobinary
sl = '123 12345 1234567 987654321 10001 -10001 -123 -100 100 -12345' -
'1 2 -1 -10 2002 -2002 0' -
'abc 1e3 -17e-3 4004.5 12345678 9876543210' -- extras
parse arg digsL digsR . if \digsL.datatype('w') then digsL = 3 if \digsR.datatype('w') then digsR = digsL if digsL > digsR then digsR = digsL
loop dc = digsL to digsR
say 'Middle' dc 'characters' loop nn = 1 to sl.words() val = sl.word(nn) say middleDigits(dc, val) end nn say end dc
return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ method middleDigits(didgitCt, val) constant
text = val.right(15)':'
even = didgitCt // 2 == 0 -- odd or even?
select
when \val.datatype('w') then text = text 'is not a whole number'
when val.abs().length < didgitCt then text = text 'has less than' didgitCt 'digits'
when \even & val.abs().length // 2 == 0 then text = text 'does not have an odd number of digits'
when even & val.abs().length // 2 \= 0 then text = text 'does not have an even number of digits'
otherwise do
val = val.abs()
valL = val.length
cutP = (valL - didgitCt) % 2
text = text val.substr(cutP + 1, didgitCt)
end
catch NumberFormatException
text = val 'is not numeric'
end
return text
</lang> Output:
Middle 3 characters
123: 123
12345: 234
1234567: 345
987654321: 654
10001: 000
-10001: 000
-123: 123
-100: 100
100: 100
-12345: 234
1: has less than 3 digits
2: has less than 3 digits
-1: has less than 3 digits
-10: has less than 3 digits
2002: does not have an odd number of digits
-2002: does not have an odd number of digits
0: has less than 3 digits
abc: is not a whole number
1e3: is not a whole number
-17e-3: is not a whole number
4004.5: is not a whole number
12345678: does not have an odd number of digits
9876543210: does not have an odd number of digits
OCaml
<lang ocaml>let even x = (x land 1) <> 1
let middle_three_digits x =
let s = string_of_int (abs x) in let n = String.length s in if n < 3 then failwith "need >= 3 digits" else if even n then failwith "need odd number of digits" else String.sub s (n / 2 - 1) 3
let passing = [123; 12345; 1234567; 987654321; 10001; -10001; -123; -100; 100; -12345] let failing = [1; 2; -1; -10; 2002; -2002; 0]
let print x =
let res = try (middle_three_digits x) with Failure e -> "failure: " ^ e in Printf.printf "%d: %s\n" x res
let () =
print_endline "Should pass:"; List.iter print passing; print_endline "Should fail:"; List.iter print failing;
- </lang>
- Output:
Should pass: 123: 123 12345: 234 1234567: 345 987654321: 654 10001: 000 -10001: 000 -123: 123 -100: 100 100: 100 -12345: 234 Should fail: 1: failure: need >= 3 digits 2: failure: need >= 3 digits -1: failure: need >= 3 digits -10: failure: need >= 3 digits 2002: failure: need odd number of digits -2002: failure: need odd number of digits 0: failure: need >= 3 digits
Perl
<lang Perl>#!/usr/bin/perl use strict ; use warnings ;
sub middlethree {
my $number = shift ;
my $testnumber = abs $number ;
my $error = "Middle 3 digits can't be shown" ;
my $numberlength = length $testnumber ;
if ( $numberlength < 3 ) {
print "$error : $number too short!\n" ;
return ;
}
if ( $numberlength % 2 == 0 ) {
print "$error : even number of digits in $number!\n" ;
return ;
}
my $middle = int ( $numberlength / 2 ) ;
print "Middle 3 digits of $number : " . substr( $testnumber , $middle - 1 , 3 ) . " !\n" ;
return ;
}
my @numbers = ( 123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345 ,
1, 2, -1, -10, 2002, -2002, 0 ) ;
map { middlethree( $_ ) } @numbers ; </lang>
- Output:
Middle 3 digits of 123 : 123 ! Middle 3 digits of 12345 : 234 ! Middle 3 digits of 1234567 : 345 ! Middle 3 digits of 987654321 : 654 ! Middle 3 digits of 10001 : 000 ! Middle 3 digits of -10001 : 000 ! Middle 3 digits of -123 : 123 ! Middle 3 digits of -100 : 100 ! Middle 3 digits of 100 : 100 ! Middle 3 digits of -12345 : 234 ! Middle 3 digits can't be shown : 1 too short! Middle 3 digits can't be shown : 2 too short! Middle 3 digits can't be shown : -1 too short! Middle 3 digits can't be shown : -10 too short! Middle 3 digits can't be shown : even number of digits in 2002! Middle 3 digits can't be shown : even number of digits in -2002! Middle 3 digits can't be shown : 0 too short!
Perl 6
<lang Perl6>sub middle-three($n) {
given $n.abs {
when .chars < 3 { "$n is too short" }
when .chars %% 2 { "$n has an even number of digits" }
default { "The three middle digits of $n are: ", .substr: (.chars - 3)/2, 3 }
}
}
say middle-three($_) for <
123 12345 1234567 987654321 10001 -10001 -123 -100 100 -12345 1 2 -1 -10 2002 -2002 0
>;</lang>
- Output:
The three middle digits of 123 are: 123 The three middle digits of 12345 are: 234 The three middle digits of 1234567 are: 345 The three middle digits of 987654321 are: 654 The three middle digits of 10001 are: 000 The three middle digits of -10001 are: 000 The three middle digits of -123 are: 123 The three middle digits of -100 are: 100 The three middle digits of 100 are: 100 The three middle digits of -12345 are: 234 1 is too short 2 is too short -1 is too short -10 is too short 2002 has an even number of digits -2002 has an even number of digits 0 is too short
Python
<lang python>>>> def middle_three_digits(i): s = str(abs(i)) length = len(s) assert length >= 3 and length % 2 == 1, "Need odd and >= 3 digits" mid = length // 2 return s[mid-1:mid+2]
>>> passing = [123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345] >>> failing = [1, 2, -1, -10, 2002, -2002, 0] >>> for x in passing + failing: try: answer = middle_three_digits(x) except AssertionError as error: answer = error print("middle_three_digits(%s) returned: %r" % (x, answer))
middle_three_digits(123) returned: '123'
middle_three_digits(12345) returned: '234'
middle_three_digits(1234567) returned: '345'
middle_three_digits(987654321) returned: '654'
middle_three_digits(10001) returned: '000'
middle_three_digits(-10001) returned: '000'
middle_three_digits(-123) returned: '123'
middle_three_digits(-100) returned: '100'
middle_three_digits(100) returned: '100'
middle_three_digits(-12345) returned: '234'
middle_three_digits(1) returned: AssertionError('Need odd and >= 3 digits',)
middle_three_digits(2) returned: AssertionError('Need odd and >= 3 digits',)
middle_three_digits(-1) returned: AssertionError('Need odd and >= 3 digits',)
middle_three_digits(-10) returned: AssertionError('Need odd and >= 3 digits',)
middle_three_digits(2002) returned: AssertionError('Need odd and >= 3 digits',)
middle_three_digits(-2002) returned: AssertionError('Need odd and >= 3 digits',)
middle_three_digits(0) returned: AssertionError('Need odd and >= 3 digits',)
>>> </lang>
REXX
<lang rexx>/* REXX ***************************************************************
- 03.02.2013 Walter Pachl
- /
sl='123 12345 1234567 987654321 10001 -10001 -123 -100 100 -12345',
'2 -1 -10 2002 -2002 0 abc 1e3 -17e-3'
Do While sl<> /* loop through test values */
Parse Var sl s sl /* pick next value */ Call mid3 s /* test it */ End
Exit mid3: Procedure Parse arg d /* take the argument */ Select /* first test for valid input */
When datatype(d)<>'NUM' Then Call error 'not a number'
When pos('E',translate(d))>0 Then Call error 'not just digits'
When length(abs(d))<3 Then Call error 'less than 3 digits'
When length(abs(d))//2<>1 Then Call error 'not an odd number of digits'
Otherwise Do /* input is ok */
dx=abs(d) /* get rid of optional sign */
ld=length(dx) /* length of digit string */
z=(ld-3)/2 /* number of digits to cut */
Say left(d,12) '->' substr(dx,z+1,3) /* show middle 3 digits */
End
End
Return
error:
Say left(d,12) '->' arg(1) /* tell about the problem */ Return
</lang> Output:
123 -> 123 12345 -> 234 1234567 -> 345 987654321 -> 654 10001 -> 000 -10001 -> 000 -123 -> 123 -100 -> 100 100 -> 100 -12345 -> 234 2 -> less than 3 digits -1 -> less than 3 digits -10 -> less than 3 digits 2002 -> not an odd number of digits -2002 -> not an odd number of digits 0 -> less than 3 digits abc -> not a number 1e3 -> not just digits -17e-3 -> not just digits
Ruby
<lang ruby>def middle_three_digits(n)
# minus sign doesn't factor into digit count, # and calling #abs acts as a duck-type assertion n = n.abs
# convert to string and find length l = (s = n.to_s).length
# check validity raise ArgumentError, "Number must have at least three digits" if l < 3 raise ArgumentError, "Number must have an odd number of digits" if l % 2 == 0
return s[l/2-1,3].to_i
end
samples = [
123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345, 1, 2, -1, -10, 2002, -2002, 0
]
width = samples.map { |n| n.to_s.length }.max
samples.each do |n|
print "%#{width}d: " % n
begin
puts "%03d" % middle_three_digits(n)
rescue ArgumentError => e
puts e.to_s
end
end</lang> Output:
123: 123
12345: 234
1234567: 345
987654321: 654
10001: 000
-10001: 000
-123: 123
-100: 100
100: 100
-12345: 234
1: Number must have at least three digits
2: Number must have at least three digits
-1: Number must have at least three digits
-10: Number must have at least three digits
2002: Number must have an odd number of digits
-2002: Number must have an odd number of digits
0: Number must have at least three digits
Rust
<lang rust>fn middle_three_digits(x: int) -> Result<~str, ~str> {
let s = int::abs(x).to_str();
let len = s.len();
if len < 3 {
Err(~"Too short")
} else if len % 2 == 0 {
Err(~"Even number of digits")
} else {
Ok(s.slice(len/2 - 1, len/2 + 2))
}
}
fn print_result(x: int) {
io::print(fmt!("middle_three_digits(%?) returned: ", x));
match middle_three_digits(x) {
Ok(move s) => io::println(fmt!("Success, %s", s)),
Err(move s) => io::println(fmt!("Failure, %s", s))
}
}
fn main() {
let passing = [123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345];
let failing = [1, 2, -1, -10, 2002, -2002, 0];
for passing.each |i| {
print_result(*i);
}
for failing.each |i| {
print_result(*i);
}
}</lang>
Output:
middle_three_digits(123) returned: Success, 123 middle_three_digits(12345) returned: Success, 234 middle_three_digits(1234567) returned: Success, 345 middle_three_digits(987654321) returned: Success, 654 middle_three_digits(10001) returned: Success, 000 middle_three_digits(-10001) returned: Success, 000 middle_three_digits(-123) returned: Success, 123 middle_three_digits(-100) returned: Success, 100 middle_three_digits(100) returned: Success, 100 middle_three_digits(-12345) returned: Success, 234 middle_three_digits(1) returned: Failure, Too short middle_three_digits(2) returned: Failure, Too short middle_three_digits(-1) returned: Failure, Too short middle_three_digits(-10) returned: Failure, Too short middle_three_digits(2002) returned: Failure, Even number of digits middle_three_digits(-2002) returned: Failure, Even number of digits middle_three_digits(0) returned: Failure, Too short
Scala
<lang scala>/**
* Optionally return the middle three digits of an integer. * * @example List(123,12345,-789,1234,12) flatMap (middleThree(_)), returns: List(123, 234, 789) */
def middleThree( s:Int ) : Option[Int] = s.abs.toString match {
case v if v.length % 2 == 0 => None // Middle three is undefined for even lengths case v if v.length < 3 => None case v => val i = (v.length / 2) - 1 Some( v.substring(i,i+3).toInt )
}
// A little test...
val intVals = List(123,12345,1234567,987654321,10001,-10001,-123,-100,100,-12345,1,2,-1,-10,2002,-2002,0)
intVals map (middleThree(_)) map {
case None => "No middle three" case Some(v) => "%03d".format(v) // Format the value, force leading zeroes
} mkString("\n") </lang>
- Output:
123 234 345 654 000 000 123 100 100 234 No middle three No middle three No middle three No middle three No middle three No middle three No middle three
UNIX Shell
<lang bash>function middle3digits {
typeset -i n="${1#-}"
typeset -i l=${#n}
if (( l < 3 )); then
echo >&2 "$1 has less than 3 digits"
return 1
elif (( l % 2 == 0 )); then
echo >&2 "$1 has an even number of digits"
return 1
else
echo ${n:$((l/2-1)):3}
return 0
fi
}
- test
testdata=(123 12345 1234567 987654321 10001 -10001 -123 -100 100 -12345 1 2 -1
-10 2002 -2002 0)
for n in ${testdata[@]}; do
printf "%10d: " $n middle3digits "$n"
done</lang>
Output:
123: 123
12345: 234
1234567: 345
987654321: 654
10001: 000
-10001: 000
-123: 123
-100: 100
100: 100
-12345: 234
1: 1 has less than 3 digits
2: 2 has less than 3 digits
-1: -1 has less than 3 digits
-10: -10 has less than 3 digits
2002: 2002 has an even number of digits
-2002: -2002 has an even number of digits
0: 0 has less than 3 digits
Vedit macro language
<lang vedit>do {
#1 = Get_Num("Enter a number, or 0 to stop: ", STATLINE)
Ins_Text("Input: ") Num_Ins(#1, COUNT, 10)
Call("MIDDLE_3_DIGITS")
Ins_Text(" Result: ") Reg_Ins(10) Ins_Newline
Update()
} while (#1); Return
// Find middle 3 digits of a number // in: #1 = numeric value // out: @10 = the result, or error text //
- MIDDLE_3_DIGITS:
Buf_Switch(Buf_Free) Num_Ins(abs(#1), LEFT+NOCR) // the input value as string
- 2 = Cur_Col-1 // #2 = number of digits
if (#2 < 3) {
Reg_Set(10, "Too few digits!")
} else {
if ((#2 & 1) == 0) {
Reg_Set(10, "Not odd number of digits!")
} else {
Goto_Pos((#2-3)/2) Reg_Copy_Block(10, Cur_Pos, Cur_Pos+3)
}
} Buf_Quit(OK) Return </lang>
Output:
Input: 123 Result: 123 Input: 12345 Result: 234 Input: 1234567 Result: 345 Input: 987654321 Result: 654 Input: 10001 Result: 000 Input: -10001 Result: 000 Input: -123 Result: 123 Input: -100 Result: 100 Input: 100 Result: 100 Input: -12345 Result: 234 Input: 1 Result: Too few digits! Input: 2 Result: Too few digits! Input: -1 Result: Too few digits! Input: -10 Result: Too few digits! Input: 2002 Result: Not odd number of digits! Input: -2002 Result: Not odd number of digits! Input: 0 Result: Too few digits!
XPL0
<lang XPL0>include c:\cxpl\stdlib;
func Mid3Digits(I); \Return the middle three digits of I int I; int Len, Mid; char S(10); [ItoA(abs(I), S); Len:= StrLen(S); if Len<3 or (Len&1)=0 then return "Must be 3, 5, 7 or 9 digits"; Mid:= Len/2; S:= S + Mid - 1; S(2):= S(2) ! $80; \terminate string return S; \WARNING: very temporary ];
int Passing, Failing, X; [Passing:= [123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345];
Failing:= [1, 2, -1, -10, 2002, -2002, 0]; \WARNING: nasty trick
for X:= 0 to 16 do
[Text(0, "Middle three digits of "); IntOut(0, Passing(X));
Text(0, " returned: ");
Text(0, Mid3Digits(Passing(X))); CrLf(0);
];
]</lang>
- Output:
Middle three digits of 123 returned: 123 Middle three digits of 12345 returned: 234 Middle three digits of 1234567 returned: 345 Middle three digits of 987654321 returned: 654 Middle three digits of 10001 returned: 000 Middle three digits of -10001 returned: 000 Middle three digits of -123 returned: 123 Middle three digits of -100 returned: 100 Middle three digits of 100 returned: 100 Middle three digits of -12345 returned: 234 Middle three digits of 1 returned: Must be 3, 5, 7 or 9 digits Middle three digits of 2 returned: Must be 3, 5, 7 or 9 digits Middle three digits of -1 returned: Must be 3, 5, 7 or 9 digits Middle three digits of -10 returned: Must be 3, 5, 7 or 9 digits Middle three digits of 2002 returned: Must be 3, 5, 7 or 9 digits Middle three digits of -2002 returned: Must be 3, 5, 7 or 9 digits Middle three digits of 0 returned: Must be 3, 5, 7 or 9 digits