gmp_scan1

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gmp_scan1 — Scan for 1

说明

gmp_scan1(GMP|int|string $num1, int $start): int

Scans num1, starting with bit start, towards more significant bits, until the first set bit is found.

参数

num1

The number to scan.

GMP 对象、int 或 string，可以按照跟在 gmp_init() 中使用字符串并自动检测 base（即当 base 等于 0 时）相同的逻辑将其解释为数字。

start

The starting bit.

返回值

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

示例

示例 #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";
?>

以上示例会输出：

3
9