gmp_scan1
(PHP 4 >= 4.0.4, PHP 5)
gmp_scan1 — Scan for 1
说明
int gmp_scan1
( resource $a
, int $start
)
Scans a , starting with bit start , towards more significant bits, until the first set bit is found.
参数
- a
-
The number to scan.
It can be either a GMP number resource, or a numeric string given that it is possible to convert the latter to a number.
- start
-
The starting bit.
返回值
Returns the index of the found bit, as an integer. If no set bit is found, -1 is returned.
范例
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";
?>
上例将输出：
3 9
