dongxia19772008 2015-05-22 02:11
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PHP按位AND(&)返回负数

The code:

echo (5243960811416 & 4040906070209050);

Try on http://phptester.net/ and the result (right) will be 20407554584

but on my web hosting it gives -1067281896.

There's any workaround to have 20407554584? It's a 32bit limit?

Thanks

UPDATE /w SOLUTION

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1条回答 默认 最新

  • dsuw85815 2015-05-25 22:58
    关注

    SOLUTION

    After searchs and searchs I found this and I re-convert in PHP

    function BitwiseAndLarge($val1, $val2) {
    
        $shift = 0; 
        $result = 0;
        $mask = ~((~0) << 30); // Gives us a bit mask like 01111..1 (30 ones)
    
        $divisor = 1 << 30; // To work with the bit mask, we need to clear bits at a time
    
        while( ($val1 != 0) && ($val2 != 0) ) {
            $rs = ($mask & $val1) & ($mask & $val2);
            $val1 = floor($val1 / $divisor); // val1 >>> 30
            $val2 = floor($val2 / $divisor); // val2 >>> 30
    
            for($i = $shift++; $i--;) {
                $rs *= $divisor; // rs << 30
            }
    
            $result += $rs;
        }
        return $result;
    }
    

    usage

    echo BitwiseAndLarge(5243960811416 & 4040906070209050);
    
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