[jina_checksum]
| Link | jina_checksum |
| Author | Jolle Carlestam |
| Category | Custom Tag |
| Version | 8.5.x |
| License | Public Domain |
| Posted | 11 Mar 2009 |
| Updated | 13 Mar 2009 |
| More by this author... | |
Description
Tag using the Luhn algorithm, a simple checksum formula, to handle checksums for a given numerical value. It can either validate that a number ends with a correct checksum or add a checksum to a number. The Luhn algorithm is used for credit card numbers, different ID numbers like in Sweden or Canada etc.
Sample Usage
jina_checksum('NNNNNNNN') will return true or false depending on if the checksum checks.
Usage with optional param -add
jina_checksum('NNNNNNNN', -add) returns the correct checksum for the checked value.
var('checkme' = '4124 9720 0139 655');
jina_checksum($checkme, -add);
-> 8
Source Code
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define_tag('checksum', -namespace = 'jina_',
-req = 'check', -copy,
-opt = 'add'
);
// tag used for the Luhn algorithm a simple checksum formula
// used to validate a variety of identification numbers
// usage jina_checksum('NNNNNNNN')
// will return true or false depending on if the checksum checks
// usage with optional param -add jina_checksum('NNNNNNNN', -add)
// returns the correct checksum for the checked value
local('temp',
'total' = integer,
'odd'
);
#check = string_replaceregexp(#check, -find = '[^0-9]', -replace = '');
if(local_defined('add'));
((#check -> size % 2) == 1 ? #odd = true | #odd = false);
else;
((#check -> size % 2) == 0 ? #odd = true | #odd = false);
/if;
loop(-from = #check -> size, -to = 1, -by = -1);
if(#odd);
#temp = integer(#check -> get(loop_count)) * ((loop_count % 2) + 1);
else;
#temp = integer(#check -> get(loop_count)) * (((loop_count + 1) % 2) + 1);
/if;
(#temp > 9 ? #temp -= 9);
#total += #temp;
/loop;
if(local_defined('add'));
return((#total % 10 == 0) ? 0 | ((#total + 10) - (#total % 10)) - #total);
else(#total % 10 == 0);
return(true);
else;
return(false);
/if;
/define_tag;
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