可以使用以下php函数，验证一个卡号是否是信用卡：
function validatecard ( $cardnumber ) { $cardnumber = preg_replace ( /\d|\s/ , , $cardnumber ) ; # strip any non-digits $cardlength = strlen ( $cardnumber ) ; if ( $cardlength != 0 ) { $parity = $cardlength % 2 ; $sum = 0 ; for ( $i = 0 ; $i 9 ) $digit = $digit - 9 ; $sum = $sum + $digit ; } $valid = ( $sum % 10 == 0 ) ; return $valid ; } return false ;}