PHP Program to Count Zeros and Ones in Binary Representation of a Number - Coding

Counting the number of zeros and ones in the binary representation of a number is a common task in computer science and programming. In this article, we will explore how to achieve this in PHP using different approaches.

Table of Content

Using Built-in Functions
Using Bitwise Operations
Using Recursive Approach

Count Zeros and Ones in Binary Representation of a Number using Built-in Functions

This PHP program uses built-in functions to efficiently count the number of zeros and ones in the binary representation of a given number. It first converts the number to binary using decbin( ), then uses substr_count( ) to count the occurrences of “0” and “1” in the binary string. The counts are returned as an associative array.

Example: Implementation to count zeros and ones in binary representation of a number.

PHP

<?php 
  
function countZeros_Ones($number) { 
    $binary = decbin($number); 
    $zeros = substr_count($binary, "0"); 
    $ones = substr_count($binary, "1"); 
  
    return ["zeros" => $zeros, "ones" => $ones]; 
} 
  
// Driver code 
$number = 10; 
$result = countZeros_Ones($number); 
  
echo "Binary representation of $number: " . decbin($number) . "\n"; 
echo "Number of zeros: " . $result["zeros"] . "\n"; 
echo "Number of ones: " . $result["ones"] . "\n"; 
  
?> 

Output

Binary representation of 10: 1010
Number of zeros: 2
Number of ones: 2

Explanation:

The decbin function converts the decimal number to its binary representation.
The substr_count( ) function counts the number of occurrences of ‘0’ and ‘1’ in the binary string.
The function returns an associative array containing the count of zeros and ones.

Count Zeros and Ones in Binary Representation of a Number using Bitwise Operations

This PHP program uses bitwise operations to count the number of zeros and ones in the binary representation of a given number. It iterates through each bit of the number, checking if it’s a zero or a one using the bitwise AND operator (‘&’). If it’s a one, it increments the $ones counter; otherwise, it increments the $zeros counter. The program then shifts the number one bit to the right (`$number >> 1`) to move to the next bit. This process continues until the number becomes zero. The counts are returned as an associative array.

Example: Implementation to count zeros and ones in binary representation of a number.

PHP

<?php 
  
function countZeros_Ones($number) { 
    $zeros = 0; 
    $ones = 0; 
  
    while ($number > 0) { 
        if ($number & 1) { 
            $ones++; 
        } else { 
            $zeros++; 
        } 
        $number = $number >> 1; 
    } 
  
    return ["zeros" => $zeros, "ones" => $ones]; 
} 
  
// Driver code 
$number = 99; 
$result = countZeros_Ones($number); 
  
echo "Binary representation of $number: " . decbin($number) . "\n"; 
echo "Number of zeros: " . $result["zeros"] . "\n"; 
echo "Number of ones: " . $result["ones"] . "\n"; 
  
?> 

Output

Binary representation of 99: 1100011
Number of zeros: 3
Number of ones: 4

Explanation:

The function uses a while loop to iterate through each bit of the number.
The & operator is used to check if the least significant bit is 1 or 0.
The >> operator is used to right shift the number by one bit in each iteration.
The function keeps a count of zeros and ones and returns them in an associative array.

Count Zeros and Ones in Binary Representation of a Number using Recursive Approach

This PHP program counts the number of zeros and ones in the binary representation of a given number using a recursive approach. It recursively divides the number by 2, counting the remainder as either a zero or a one, until the number becomes zero. The counts are returned as an associative array.

Example: Implementation to count zeros and ones in binary representation of a number.

PHP

<?php 
  
function countSetBits($n) { 
    // Base case: if n is 0, return 0 
    if ($n == 0) 
        return 0; 
    else
        // If the last bit is set, add 1; otherwise, add 0 
        return ($n & 1) + 
                countSetBits($n >> 1); 
} 
  
function countUnsetBits($n) { 
    // Base case: if n is 0, return 0 
    if ($n == 0) 
        return 0; 
    else
        // If the last bit is set, add 0; otherwise, add 1 
        return !($n & 1) + 
                countUnsetBits($n >> 1); 
} 
  
// Get value from user 
$n = 99; 
  
// Function calling 
echo "Number of Ones in $n are: ".countSetBits($n)."\n"; 
echo "Number of Zeroes in $n are: ".countUnsetBits($n)."\n"; 
?> 

Output

Number of Ones in 99 are: 4
Number of Zeroes in 99 are: 3

Explanation

The code uses a recursive approach to count the number of ones and zeroes in the binary representation of a given number $n.
Both functions countSetBits and countUnsetBits return zero when $n is zero, as there are no bits to count.
The code uses bitwise AND (`&`) and right shift (`>>`) operations to check the last bit of `$n`. If the last bit is set (i.e., it’s a one), the function increments the count of ones. If the last bit is not set (i.e., it’s a zero), the function increments the count of zeroes.
The code demonstrates the usage of the two functions by calling them with a sample value of `$n` (99 in this case). It then prints the count of ones and zeroes in the binary representation of `$n`.

Reffered: https://www.geeksforgeeks.org

PHP

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