(PHP 4 >= 4.0.4, PHP 5)
gmp_com — Calculates one's complement
$a
)
Returns the one's complement of a.
a
可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。
Returns the one's complement of a, as a GMP number.
Example #1 gmp_com() example
<?php
$com = gmp_com("1234");
echo gmp_strval($com) . "\n";
?>
以上例程会输出：
-1235
xo at jdbartlett dot com (2010-04-13 22:07:14)
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)