(PHP 4 >= 4.0.4, PHP 5)
gmp_setbit — Set bit
$a
, int $index
[, bool $set_clear = true
] )
Sets bit index in a.
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。
index
The set bit.
set_clear
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
<?php
$a = gmp_init("0xfd");
gmp_setbit($a, 1); // index starts at 0
echo gmp_strval($a) . "\n";
?>
以上例程会输出：
255
Note:
Unlike most of the other GMP functions, gmp_setbit() must be called with a GMP resource that already exists (using gmp_init() for example). One will not be automatically created.
bluej100@gmail (2007-07-27 09:07:47)
The third parameter is somewhat confusingly named; it would probably be better described as "$set_state". If true, it sets the bit to 1. If false, it sets the bit to 0. Default is true.
<?php
$num = gmp_init(1);
gmp_setbit($num, 1);
echo 'gmp_setbit(1, 1): '.gmp_strval($num, 2)."\n"; // 11
$num = gmp_init(1);
gmp_setbit($num, 1, true);
echo 'gmp_setbit(1, 1, true): '.gmp_strval($num, 2)."\n"; // 11
$num = gmp_init(1);
gmp_setbit($num, 0, false);
echo 'gmp_setbit(1, 0, false): '.gmp_strval($num, 2)."\n"; // 0
?>