gmp_com

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

gmp_com — Calculates one's complement

说明

gmp_com ( GMP $a ) : GMP

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 13-Apr-2010 10:07


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)