php man page for gmp_scan1

GMP_SCAN1(3)								 1							      GMP_SCAN1(3)

gmp_scan1 - Scan for 1

SYNOPSIS
       int gmp_scan1 (GMP  $a, int  $start)

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

PARAMETERS
	      o $a
		-  The number to scan. Either a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 5.6 and later, or a numeric string
		provided that it is possible to convert the latter to a number.

	      o $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(3) example

	      <?php
	      // "1" bit is found at position 3. index starts at 0
	      $s1 = gmp_init("01000", 2);
	      echo gmp_scan1($s1, 0) . "
";

	      // "1" bit is found at position 9. index starts at 5
	      $s2 = gmp_init("01000001111", 2);
	      echo gmp_scan1($s2, 5) . "
";
	      ?>

	      The above example will output:

	      3
	      9

PHP Documentation Group 													      GMP_SCAN1(3)