Never been to DZone Snippets before?

Snippets is a public source code repository. Easily build up your personal collection of code snippets, categorize them with tags / keywords, and share them with the world

« Newer Snippets
Older Snippets »
Showing 1-1 of 1 total  RSS 

Luhn Credit card checksum function

luhn: func [    ; tested out OK.
    card-num [string!]
    /local cksum flag val
] [
    cksum: 0
    flag: even? length? card-num
    foreach digit card-num [
        val: to integer! form digit
        if flag [
            val: val * 2
            if val > 9 [val: val - 9]
            ; - alt -
            ;val: pick [0 2 4 6 8 1 3 5 7 9] val + 1
        ]
        cksum: cksum + val
        flag: not flag
    ]
    print cksum
    0 = remainder cksum 10
]

;print luhn "4005550000000019"
to checksum REBOL luhn credit card by gregg.irwin on Jan 12, 2006
« Newer Snippets
Older Snippets »
Showing 1-1 of 1 total  RSS