PHP5中文手册·Scan for 1 -- 追寻梦想＞编程乐园＞PHP 编程

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


	PHP5中文手册 gmp_scan0 gmp_setbit GMP PHP Manual 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 gmp_scan0 gmp_setbit GMP PHP Manual