/**
* Luhn-Algorithm for Creditcards an Bankaccounts
* Creditcards exposure is everytime 2121… in length of the cardnumber
* Banknumbers will have for each bank a own exposure.
* I hope all Verificationnumbers will be calculatet for Bankaccounts with this algorithm.
* In Some Cases the modulo have to be changed. On Creditcards the module everytime is 10.
* Please report bugs to doubleatdumpitde
*
* @param string $nb have to be string and numeric because double is to small
* @param string $exp have to be string and numeric because double is to small
* @param int $mod used modulo
* @return boolean
*/
function _luhn( $nb, $exp = ’2121212121212121′, $mod = 10 )
{
// first validate parameters
if( !is_string( $nb ) )
return PEAR::raiseError( ‘given parameter nb (number) is not a string’, null );
if( !is_string( $exp ) )
return PEAR::raiseError( ‘given parameter exp (exposure) is not a string’, null );
if( !is_numeric( $nb ) )
return PEAR::raiseError( ‘given parameter nb (number) is not numeric’, null );
if( !is_numeric( $exp ) )
return PEAR::raiseError( ‘given parameter exp (exposure) is not numeric’, null );
if( !is_integer( $mod ) )
return PEAR::raiseError( ‘given parameter mod (modulo) is not numeric’, null );
if( 0 >= $nb )
return PEAR::raiseError( ‘given parameter nb (number) could not be lower than or zero’, null );
if( strlen($exp) != strlen( $nb ) )
return PEAR::raiseError( ‘given parameter exp (exposure) is not in characterlength of nb (number)’, null );

// lets do the calculation
for( $sum = 0, $pos = 0; $pos < strlen( $nb ); $pos++ )
{
$x = $exp[$pos]*$nb[$pos];
$sum += 9 > $x ? $x : substr($x,0,1)+substr($x,1,1);
}
return(0<$sum&&0==$sum%$mod);
}

isn’t it easy ;)

… think big ppl ;)

/**
* Luhn-Algorithm for Creditcards an Bankaccounts
* Creditcards exposure is everytime 1212… in length of the cardnumber
* Banknumbers will have for each bank a own exposure.
* I hope all Verificationnumbers will be calculatet for Bankaccounts with this algorithm.
* In Some Cases the modulo have to be changed. On Creditcards the module everytime is 10.
* Please report bugs to doubleatdumpitde.
*
* @param string $nb have to be string and numeric because double is to small
* @param string $exp have to be string and numeric because double is to small
* @param int $mod used modulo
* @return boolean
*/
function _luhn( $nb, $exp = ’1212121212121212′, $mod = 10 )
{
// first validate parameters
if( !is_string( $nb ) )
return PEAR::raiseError( ‘given parameter nb (number) is not a string’, null );
if( !is_string( $exp ) )
return PEAR::raiseError( ‘given parameter exp (exposure) is not a string’, null );
if( !is_numeric( $nb ) )
return PEAR::raiseError( ‘given parameter nb (number) is not numeric’, null );
if( !is_numeric( $exp ) )
return PEAR::raiseError( ‘given parameter exp (exposure) is not numeric’, null );
if( !is_integer( $mod ) )
return PEAR::raiseError( ‘given parameter mod (modulo) is not numeric’, null );
if( 0 >= $int )
return PEAR::raiseError( ‘given parameter nb (number) could not be lower than or zero’, null );
if( strlen($exp) != strlen( $int ) )
return PEAR::raiseError( ‘given parameter exp (exposure) is not in characterlength of nb (number)’, null );

// lets do the calculation
for( $sum = 0, $pos = 0; $pos = $x ? $x : $x[0]+$x[1];
}

return(0==$sum%$mod);
}

Thanks,

Mike

-L