SYNOPSIS
use Algorithm::CheckDigits;
$sici = CheckDigits('sici');
if ($sici->is_valid('0784-8679(20040308)6:<138>2.0.TX;2-H')) {
# do something
}
$cn = $sici->complete('0784-8679(20040308)6:<138>2.0.TX;2-');
# $cn = '0784-8679(20040308)6:<138>2.0.TX;2-H'
$cd = $sici->checkdigit('0784-8679(20040308)6:<138>2.0.TX;2-H');
# $cd = 'H'
$bn = $sici->basenumber('0784-8679(20040308)6:<138>2.0.TX;2-H');
# $bn = '0784-8679(20040308)6:<138>2.0.TX;2-';
DESCRIPTION
ALGORITHM
- 0
- In the string describing the number all letters (A-Z) are replaced with numbers 10-35 accordingly. All other non-numbers are replaced by 36.
- 1
- Beginning right the numbers at all odd positions are added.
- 2
- The sum from step 1 is multiplied by 3.
- 3
- Beginning right the numbers at all even positions are added.
- 4
- The sums from step 2 and 3 are added.
- 5
- The sum from step 4 is taken modulo 37.
- 6
- The checksum is 37 minus the sum from step 5 where numbers from 10 to 35 are represented by 'A' to 'Z' accordingly and 36 is represented by '#'.
METHODS
- is_valid($number)
-
Returns true only if $number consists solely of numbers and hyphens
and the two digits in the middle
are valid check digits according to the algorithm given above.
Returns false otherwise,
- complete($number)
-
The check digit for $number is computed and inserted into the
middle of $number.
Returns the complete number with check digit or '' if $number does not consist solely of digits, hyphens and spaces.
- basenumber($number)
-
Returns the basenumber of $number if $number has a valid check
digit.
Return '' otherwise.
- checkdigit($number)
-
Returns the check digits of $number if $number has valid check
digits.
Return '' otherwise.