gmp_cmp

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gmp_cmp — Compare numbers

说明

gmp_cmp ( GMP|int|string $num1 , GMP|int|string $num2 ) : int

Compares two numbers.

参数

num1: GMP 对象或 int ，或数字string。
num2: GMP 对象或 int ，或数字string。

返回值

Returns a positive value if a > b, zero if a = b and a negative value if a < b.

范例

Example #1 gmp_cmp() example


<?php
$cmp1 = gmp_cmp("1234", "1000"); // greater than
$cmp2 = gmp_cmp("1000", "1234"); // less than
$cmp3 = gmp_cmp("1234", "1234"); // equal to

echo "$cmp1 $cmp2 $cmp3\n";
?>

以上例程会输出：

1 -1 0

User Contributed Notes

russell dot harper at springboardnetworks dot com 28-Jul-2010 01:43


I've encountered a memory leak in gmp_cmp if a literal string is used as the second value inside of loops. A workaround is to initialize first, then use the variable. I wasn't able to generate a minimum code sample, it's something more complicated, but I was able to fix it as follows:



<?php



$x = gmp_init(strval(mt_rand()));



// Depending on surrounding code, may have leaks

while (true)

{

    if (!gmp_cmp($x, '1'))

        print 'one'."\n";

}



// Usually doesn't have leaks

$one = gmp_init('1');



while (true)

{

    if (!gmp_cmp($x, $one))

        print 'one'."\n";

}



?>