Sha256: b5b82b1737b4c608c2a6f181193543320cfae2422e106b0b5cea282c635cb0a8
Contents?: true
Size: 769 Bytes
Versions: 84
Compression:
Stored size: 769 Bytes
Contents
-module(luhn).
-export([valid/1, create/1, checksum/1]).
checksum(Number) ->
checksum(
lists:reverse(
lists:filter(
fun(C) ->
($0 =< C) andalso (C =< $9)
end,
Number
)
),
odd,
0
).
checksum([], _, Total) ->
Total;
checksum([H | ReversedNumber], odd, Total) ->
checksum(ReversedNumber, even, Total + H - $0);
checksum([H | ReversedNumber], even, Total) when H < $5 ->
checksum(ReversedNumber, odd, Total + (H - $0) * 2);
checksum([H | ReversedNumber], even, Total) when H >= $5 ->
checksum(ReversedNumber, odd, Total + ((H - $0) * 2) - 9).
valid(Number) ->
checksum(Number) rem 10 == 0.
create(Number) ->
lists:flatten([Number, ($: - (checksum(Number ++ [$0]) rem 10))]).
Version data entries
84 entries across 84 versions & 1 rubygems