字符串转整形

function ($str)  
{  
    $seed = 131; 
    $hash = 0;  
    $cnt = strlen($str);  
    for($i = 0; $i < $cnt; $i++)  
    {  
        $hash = ((floatval($hash * $seed) & 0x7FFFFFFF) + ord($str[$i])) & 0x7FFFFFFF;  
    }  
    return ($hash & 0x7FFFFFFF);  
}