PHP | gmp_scan1() Function

The gmp_scan1() is an inbuilt function which is used to scan “1” in the GMP number(GNU Multiple Precision : For large numbers) starting from given index which move towards most significant bits in the number.

Syntax:

gmp_scan1($num, $index)

Parameters: This function accepts two parameters as explained below:

• $num: This parameter is a GMP number and is mandatory to be passed. This parameter can be a GMP object in PHP version 5.6 and later, or we are also allowed to pass a numeric string provided that it is possible to convert that string to a number.
• $index: This parameter represents the index or position in the bitwise representation of the number $num from where we want to start the search.

Return Value: The function returns the position where we find “1” in the number.

Examples:

Input : gmp_scan1("101111101", 6)
Output : 8

Input : gmp_scan1("111001111", 2)
Output : 3

Below programs illustrate the gmp_scan1() function in PHP:

Program 1: Program to find the position of “1” bit in GMP number when numeric strings as GMP numbers are passed as arguments.

<?php

// PHP program to find position of "1" bit in GMP
// number passed as arguments

// strings as GMP numbers
$num = "10110001";
$pos = 2;


echo gmp_scan1($num, $pos) . "\n";

?>

Output:

4

Program 2: Program to find the position of “1” bit in GMP number when GMP numbers are passed as arguments.

<?php
// PHP program to find position of "1" bit in GMP
// number

//creating GMP numbers using gmp_init()
$num = gmp_init(10001111101);
$pos = 2;

echo gmp_scan1($num, $pos) . "\n";

?>

Output:

3

Reference:
http://php.net/manual/en/function.gmp-scan1.php