PHP 10进制和36进制转换

decimal.php

if (!function_exists('base36_encode')) {
    /**
     * 十进制数转换成三十六进制数
     * @param (int)$num : 十进制数
     * return (string) :三十六进制数
    */
    function base36_encode($num) 
    {
        $num = intval($num);
        if ($num < 0)
        {
            return false;
        }
        $charArr = array('0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');
        $char = '';
        do
        {
            $key = bcmod($num , 36);
            $char= $charArr[$key] . $char;
            $num = bcdiv(($num - $key),36, 0);
        }
        while ($num > 0);
        return $char;
    }
}

if (!function_exists('base36_decode')) {
    /**
     * 三十六进制数转换成十进制数
     * @param (string)$char :三十六进制数
     * return (int) :十进制数
     */
    function base36_decode($char){
        $charArr = array('0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');
        $len = strlen($char);
        $sum = 0;
        for($i=0; $i<$len; ++$i)
        {
            $index = array_search( $char[$i], $charArr);
            $sum = bcadd($sum, bcmul($index, bcpow(36, $len-$i-1, 0)));
        }
        return $sum;
    }
}

<?php

        // 测试用例
        $i = 88888888;
        $b36 = base36_encode($i);
        echo $i . ' = ' . $b36 . "\n";
        $x = base36_decode($b36);
        if ($x != $i) {
            echo 'error, x:' . $x . ' != i:' . $i. "\n";
        }

        $i = 0x7FFFFFFF;
        $b36 = base36_encode($i);
        echo $i . ' = ' . $b36 . "\n";
        $x = base36_decode($b36);
        if ($x != $i) {
            echo 'error, x:' . $x . ' != i:' . $i. "\n";
        }

        $i = 0xFFFFFFFF;
        $b36 = base36_encode($i);
        echo $i . ' = ' . $b36 . "\n";
        $x = base36_decode($b36);
        if ($x != $i) {
            echo 'error, x:' . $x . ' != i:' . $i. "\n";
        }

        $i = PHP_INT_MAX;
        $b36 = base36_encode($i);
        echo $i . ' = ' . $b36 . "\n";
        $x = base36_decode($b36);
        if ($x != $i) {
            echo 'error, x:' . $x . ' != i:' . $i. "\n";
        }