Luhn test of credit card numbers: Difference between revisions

=={{header|Picat}}==

<lang Picat>go =>

Nums = ["49927398716","49927398717","1234567812345678","1234567812345670"],

foreach (N in Nums)

println([N, isluhn10(N)])

end,

nl.

%

% isluhn10(num) returns 1 is valid, else 0

%

% Assumption: input num is a string.

%

isluhn10(Num) = V =>

X = [I : I in Num.reverse()] ++ [""],

Digits = "0246813579",

M = new_map([(I.to_string()=Digits[I+1]) : I in 0..9]),

V1 = sum([X[I].to_integer() + M.get2(X[I+1].to_string(),0) : I in 1..2..Num.length]),

V := cond(V1 mod 10 == 0, 1, 0).

% A variant of Map.get with conversions

get2(M, Key, Default)=V =>

if M.has_key(Key) then V= M.get(Key).to_integer() else V=Default end.</lang>

Output:

<pre>[49927398716,1]

[49927398717,0]

[1234567812345678,0]

[1234567812345670,1]</pre>