PHP | gmp_setbit() Function

The

gmp_setbit() function

is an inbuilt function in PHP which is used to set the bit index in given $num.

Syntax:

void gmp_setbit( GMP $num, int $index, bool $bit_on )

Parameters:

This function accepts three parameters as mentioned above and described below:

• $num: It is a required parameter. This parameter gives the value to be modified. This parameter can be a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 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: It is a required parameter. This parameter provides the index to be set. Here index 0 represents the least significant bit.
• $set_state: This parameter sets the bits, if "True" it sets the bit to 1/on and if "False", it will clear the bit that is set the bit to 0/off.

Return Value:

This function returns the

number resource in PHP 5.5 and earlier, or a GMP object in PHP 5.6 and later.

Program 1:

Program to illustrate

gmp_setbit()

function having index 0:

<?php
// PHP program to demonstrate the gmp_setbit() function
// with index 0

// It will create a gmp number
$num = gmp_init("2");  

// gmp_strval will return the string value of a GMP number
// when the argument is numeric string and 
// the second parameter is present 
echo gmp_strval($num), ' -> 0b', gmp_strval($num, 2), "\n"; 

gmp_setbit($num, 0);  // 0b10 now becomes 0b11

echo gmp_strval($num), ' -> 0b', gmp_strval($num, 2);
?>

Output:

2 -> 0b10
3 -> 0b11

Program 2:

Program of

gmp_setbit()

function for clearing the bit:

<?php

// php program to illustrate gmp_setbit() function
// for clearing bit

// gmp_init() will create a gmp number
$num = gmp_init("3");

// gmp_strval will return the string value of a GMP number
// when the argument is numeric string and 
// the second parameter is present 
echo gmp_strval($num), ' -> 0b', gmp_strval($num, 2), "\n";

gmp_setbit($num, 0, false); // clearing bit at index 0

echo gmp_strval($num), ' -> 0b', gmp_strval($num, 2);
?>

Output :

3 -> 0b11
2 -> 0b10

Reference: