(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_scan1 — Scan for 1
Scans num1, starting with bit
start, towards more significant bits,
until the first set bit is found.
num1The 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。
startThe starting bit.
Returns the index of the found bit, as an int. If no set bit is found, -1 is returned.
Throws a ValueError if start is negative or, as of PHP 8.5.0, too large.
Prior to PHP 8.0.0, an E_WARNING was raised instead.
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