文字
gmp_testbit
(PHP 5, PHP 7 >= 5.3.0)
gmp_testbit — Tests if a bit is set
说明
bool gmp_testbit
( GMP
$a
, int $index
)Tests if the specified bit is set.
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。
-
index -
The bit to test
返回值
Returns TRUE if the bit is set in resource $a,
otherwise FALSE .
错误／异常
An E_WARNING level error is issued when
index is less than zero, and FALSE
is returned.
范例
Example #1 gmp_testbit() example
<?php
$n = gmp_init ( "1000000" );
var_dump ( gmp_testbit ( $n , 1 ));
gmp_setbit ( $n , 1 );
var_dump ( gmp_testbit ( $n , 1 ));
?> 以上例程会输出：
bool(false) bool(true)
参见
- gmp_setbit() - Set bit
- gmp_clrbit() - Clear bit
用户评论:
[#1] bluej100@gmail [2007-07-19 14:48:38]
gmp_testbit will be very useful for my (over 64-bit) bitmask checking.
In the meantime, I think these are the best replacements.
Mostly full:
<?php
(gmp_scan1($a, $index) == $index)
?>
Mostly empty:
<?php
(gmp_scan0($a, $index) != $index)
?>
Still worst-case O(N), though.