(PHP 4 >= 4.0.4, PHP 5)
gmp_scan1 — Scan for 1
$a
, int $start
)
Scans a, starting with bit
start, towards more significant bits,
until the first set bit is found.
a
The number to scan.
可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。
start
The starting bit.
Returns the index of the found bit, as an integer. If no set bit is found, -1 is returned.
Example #1 gmp_scan1() example
<?php
// "1" bit is found at position 3. index starts at 0
$s1 = gmp_init("01000", 2);
echo gmp_scan1($s1, 0) . "\n";
// "1" bit is found at position 9. index starts at 5
$s2 = gmp_init("01000001111", 2);
echo gmp_scan1($s2, 5) . "\n";
?>
以上例程会输出：
3 9