gmp_com

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

gmp_com — Calculates one's complement

说明

GMP gmp_com ( GMP $a )

Returns the one's complement of a.

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。

返回值

Returns the one's complement of a, as a GMP number.

范例

Example #1 gmp_com() example

<?php
$com = gmp_com("1234");
echo gmp_strval($com) . "\n";
?>

以上例程会输出：

-1235

User Contributed Notes

xo at jdbartlett dot com 14-Apr-2010 07:07
If you're using one's compliment (bitwise NOT) to flip all $a's bits, don't forget that you need to use a mask to specify how many bits you expect in your result:

<?php gmp_and(gmp_com('1234'), '2047') ?>
>> 813 // 01100101101 in binary

I chose 2047 because 1234 is an 11-bit binary number and 2047 is the maximum an 11-bit register can hold:

11111111111  (2047)
10011010010  (1234)
01100101101  (813)