gmp_cmp

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

gmp_cmp — Compare numbers

说明

gmp_cmp ( GMP $a , GMP $b ) : int

Compares two numbers.

参数

a

可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。

b

可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。

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";
}

?>