(PHP 4 >= 4.0.4, PHP 5)
gmp_setbit — Set bit
Sets bit index in a.
The number being set to.
可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。
The set bit.
Defines if the bit is set to 0 or 1. By default the bit is set to 1. Index starts at 0.
GMP 数值资源.
Example #1 gmp_setbit() example 以上例程会输出：
<?php
$a = gmp_init("0xfd");
gmp_setbit($a, 1); // index starts at 0
echo gmp_strval($a) . "
";
?>
255
Note:
Unlike most of the other GMP functions, gmp_setbit() must be called with a GMP resource that already exists (using gmp_init() for example). One will not be automatically created.