gmp_scan1()

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

Scan for 1

说明

gmp_scan1(GMP$a,int $start): int

Scans$a, starting with bit$start, towards more significant bits, until the first set bit is found.

参数

$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.

返回值

Returns the index of the found bit, as an integer. If no set bit is found,-1 is returned.

范例

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