gmp_scan1

Scan for 1 (PHP 4 >= 4.0.4, PHP 5)
int gmp_scan1 ( resource a, int start )

Scans a, starting with bit start, towards more significant bits, until the first set bit is found. Returns the index of the found bit. If no set bit is found, -1 is returned.

例 692. 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 printout of the above program will be:

3
9