PHP CUSIP 校验码

Question

我需要能够根据他们的校验位来验证 CUSIP 号码。多亏了维基百科，我有了这个过程的伪代码，但到目前为止我还无法在 PHP 中复制它。

可以找到伪代码here .

我的PHP:

    <?php
/**
    * function to return the check digit value of a cusip
    * @param $cusip
    *       the cusip for processing.
    * @return Int
    *       cusip check digit.
    */
    function cusip_checksum($cusip){
        $sum = 0;
        $rebuiltcusip = '';
        for($i = 1; $i <= 8; $i++){
            $c = substr($cusip, ($i - 1), 1); //$i needs to be 0, so as we start at 1, take 1 off.
            $rebuiltcusip .= $c;
            switch(true){
                case $c == '0': // ctype_digit(0) returns false, so checking for 0 here.
                    $v = $c;
                    watchdog("case 0: ", $v);
                break;
                case ctype_digit($c): //check if numeric
                    $v = $c;
                    watchdog("case ctype_digit: ", $v);
                break;
                case $c == '*':
                    $v = 36;
                    watchdog("case *: ", $v);
                break;
                case $c == '@':
                    $v = 37;
                    watchdog("case @: ", $v);
                break;
                case $c == '#':
                    $v = 38;
                    watchdog("case #: ", $v);
                break;
                case !ctype_digit($c): //check letter last as this check would pass with * @ or # so allow them to be checked first
                    $v = (ord($c) - 64) + 9; //set ordinal number, -64 as this returns ASKII value, then add 9.
                    watchdog("case not ctype_digit: ", $v);
                break;
            }
            if(($i % 2) == 0){ //check if odd
                $v = $v * 2;
                watchdog("case odd: ", $v);
            }

            $sum = $sum + ($v / 10) + ($v % 10);
            watchdog("sum end loop: ", $sum);
        }

        $ncd = (10 - ($sum % 10)) % 10;
        $rebuiltcusip .= $ncd;
        watchdog("rebuilt cusip: ", "Cusip: ".$cusip." Rebuilt: ".$rebuiltcusip);
        return $ncd;
    }
?>

watchdog 只是我记录过程。

传入校验位值为 8 的 CUSIP:98986T108，实际返回值为 98986T104(校验位值为 4)。

所以:

<?php
    print cusip_checksum('98986T108');
?>

应该返回 8，它返回 4。

有人能找出原因吗？

Answer 1

将除法包装在 floor() 函数中，您就在那里:

$sum = $sum + floor($v / 10) + ($v % 10);

现在 CUSIP 中的 Q 的值为 26。这会将 2 和 6 添加到 $sum 而不是添加 2.6 和 6。

这是经过更正的最终函数。我已经通过路透社提取的 17614 个 CUSIP 运行了这个，有 11 个不匹配。这是我通常从路透社数据中看到的错误级别，因此我对例程有信心。

/**
* function to return the check digit value of a cusip
* @param $cusip
*       the cusip for processing.
* @return Int
*       cusip check digit.
*/
function cusip_checksum($cusip){
    $sum = 0;
    $rebuiltcusip = '';
    for($i = 1; $i <= 8; $i++){
        $c = substr($cusip, ($i - 1), 1); //$i needs to be 0, so as we start at 1, take 1 off.
        $rebuiltcusip .= $c;
        switch(true){
            case $c == '0': // ctype_digit(0) returns false, so checking for 0 here.
                $v = $c;
                watchdog("case 0: ", $v);
            break;
            case ctype_digit($c): //check if numeric
                $v = $c;
                watchdog("case ctype_digit: ", $v);
            break;
            case $c == '*':
                $v = 36;
                watchdog("case *: ", $v);
            break;
            case $c == '@':
                $v = 37;
                watchdog("case @: ", $v);
            break;
            case $c == '#':
                $v = 38;
                watchdog("case #: ", $v);
            break;
            case !ctype_digit($c): //check letter last as this check would pass with * @ or # so allow them to be checked first
                $v = (ord($c) - 64) + 9; //set ordinal number, -64 as this returns ASKII value, then add 9.
                watchdog("case not ctype_digit: ", $v);
            break;
        }
        if(($i % 2) == 0){ //check if odd
            $v = $v * 2;
            watchdog("case odd: ", $v);
        }

        $sum = $sum + floor($v / 10) + ($v % 10);
        watchdog("sum end loop: ", $sum);
    }

    $ncd = (10 - ($sum % 10)) % 10;
    $rebuiltcusip .= $ncd;
    watchdog("rebuilt cusip: ", "Cusip: ".$cusip." Rebuilt: ".$rebuiltcusip);
    return $ncd;
}