PHP Manual: Scan for 1

Description

int gmp_scan1 ( resource $a , int $start )

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

Parameters

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.

Return Values

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

Examples

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";
?>

The above example will output:

3
9