PHP | gmp_clrbit() Function

The gmp_clrbit() function is an in-built function in PHP which clears a bit of a GMP number (GNU Multiple Precision). The gmp_clrbit() function sets the bit at a specified index in a GMP number to 0. The index starts at zero from the least significant bit.

Syntax :

gmp_clrbit( $num, $index )

Parameters: The function accepts two mandatory parameters $num and $index as shown in the above syntax. These parameters are :-

• $num : It can be either a GMP number resource in PHP 5.5 or a GMP object in PHP version 5.6 and later, or numeric strings can be passed to the function provided that it is possible to convert those strings to numbers.
• $index : The index of the bit to be cleared.The indexing starts from 0 where index 0 represents the least significant bit..

Return Values : This function returns a GMP number (in PHP 5.5 and earlier) or a GMP object (in PHP 5.6 and later) which is the number formed after the bit at the specified index is set to 0.

Examples :

Input : $num = 255, $index = 0
Output : 254

Input : $num = 128, $index = 7
Output : 0

Below programs illustrate the gmp_clrbit() function :

Program 1:

<?php
// PHP program to illustrate
// gmp_clrbit() function
$num = gmp_init(255);

gmp_clrbit($num, 0); // index starts at 0, least significant bit

echo gmp_strval($num);
?>

Output:

254

Program 2:

<?php
// PHP program to illustrate
// gmp_clrbit() function
$num = gmp_init("314567128");

gmp_clrbit($num, 8); // index starts at 0, least significant bit

echo gmp_strval($num);
?>

Output:

314566872

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