PHP | gmp_testbit() Function (original) (raw)

Last Updated : 11 Jul, 2025

The gmp_testbit() is an in-built function in PHP which checks if the specified bit of a given GMP number(GNU Multiple Precision: For large numbers) is set or not.Syntax:

gmp_testbit($num, $index)

Parameters: The function accepts two parameters which are mandatory and are described below:

  1. $num - The This function accepts one GMP number $num whose specified bit is to be checked.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.
  2. $index- The specified index whose bit in $num is to be checked. It is an integer.

Return Value: The function returns true if the specified $index bit is set, otherwise it returns false if the bit is not set. Examples:

Input : num=4num=4 num=4index=2 Output : true

Input : num=9num=9 num=9index=2 Output : false

Below programs illustrate the use of gmp_testbit() function:Program 1: The program below demonstrates the working of gmp_testbit() function when GMP number is passed as an argument.

php `

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Output:

bool(false) bool(true)

Program 2: The program below demonstrates the working of gmp_testbit() when numeric string is passed as an argument.

php `

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Output:

bool(false) bool(true)

Reference: https://www.php.net/manual/en/function.gmp-testbit.php