Scan for 1

# gmp_scan1

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

gmp_scan1 — Scan for 1

### 说明

function 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

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