PHP | gmp_popcount() Function
Last Updated :
11 Jul, 2025
The gmp_popcount() is a built-in function in PHP which is used to find the population count of a GMP number (
GNU Multiple Precision : For large numbers). We can also say that this function is used to find the number of set bits in the binary representation of a GMP number.
Syntax:
gmp_popcount ( $num )
Parameters: This function accepts a GMP number
$num as a mandatory parameter as shown in the above syntax. 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.
Return Value: This function returns an integer which is the population count or the number of set bits in binary representation of a GMP number passed to it as parameter.
Examples:
Input : "9"
Output : 2
Input : "25"
Output : 3
Below programs illustrate the gmp_popcount() function in PHP :
Program 1: Program to calculate the population count of a number when numeric strings as GMP numbers are passed as arguments.
php
<?php
// PHP program to calculate population count
// of a GMP number passed as arguments
// strings as GMP numbers
$num1 = "9";
$num2 = "25";
// calculates the population count of a number
$pcount = gmp_popcount($num1);
echo $pcount."\n";
// calculates the population count of a number
$pcount = gmp_popcount($num2);
echo $pcount."\n";
?>
Output:
2
3
Program 2: Program to calculate the population count of a number when GMP numbers are passed as arguments.
php
<?php
// PHP program to calculate population count
// of a GMP number passed as arguments
// creating GMP numbers using gmp_init()
$num1 = gmp_init(9, 10);
$num2 = gmp_init(25, 10);
// calculates the population count of a number
$pcount = gmp_popcount($num1);
echo $pcount."\n";
// calculates the population count of a number
$pcount = gmp_popcount($num2);
echo $pcount."\n";
?>
Output:
2
3
Reference:
https://www.php.net/manual/en/function.gmp-popcount.php