Validate International Securities Identification Number: Difference between revisions

=={{header|BASIC256}}==

<syntaxhighlight lang="vbnet">array base 1

dim test_set$(7)

test_set$ = {"US0378331005", "US0373831005", "U50378331005", "US03378331005", "AU0000XVGZA3", "AU0000VXGZA3", "FR0000988040"}

for i = 1 to test_set$[?]

test_str$ = ""

l = length(test_set$[i])

if l <> 12 then

print test_set$[i]; " Invalid, length <> 12 char."

continue for

end if

if asc(mid(test_set$[i], 1, 1)) < asc("A") or asc(mid(test_set$[i], 2, 1)) < asc("A") then

print test_set$[i]; " Invalid, number needs to start with 2 characters"

continue for

end if

for n = 1 to l

x = asc(mid(test_set$[i], n, 1)) - asc("0")

if x > 9 then x -= 7

if x < 10 then

test_str$ += string(x)

else # two digest number

test_str$ += string(x \ 10) + string(x mod 10)

end if

next

print test_set$[i]; " ";

if luhntest(test_str$) = 1 then

print "Invalid, checksum error"

else

print "Valid"

end if

next

end

function luhntest(cardnr$)

cardnr$ = trim(cardnr$) # remove spaces

l = length(cardnr$)

s1 = 0

s2 = 0

# sum odd numbers

for i = 1 to l step 2

s1 += fromradix(asc(mid(cardnr$, i, 1)), 10)

next

# sum even numbers

for i = 2 to l step 2

j = fromradix(asc(mid(cardnr$, i, 1)), 10)

j *= 2

if j > 9 then j = (j mod 10) + 1

s2 += j

next

return (s1 + s2) mod 10 = 0

end function</syntaxhighlight>

{{out}}

<pre>Similar to FreeBASIC entry.</pre>