PHP Program to Check Happy Number

Posted in PHP Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 48 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the domain of programming, certain mathematical properties and patterns are often explored. One such interesting concept is the notion of "happy numbers."

In this tutorial, we'll delve into a PHP program designed to check whether a given number is a happy number.

📄 Example

Let's take a look at the PHP code that checks whether a given number is a happy number or not.

isHappyNumber.php

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<?php
// Function to calculate the sum of squares of digits
function sumOfSquares($n)
{
  $sum = 0;
  while ($n > 0)
  {
    $digit = $n % 10;
    $sum += $digit * $digit;
    $n /= 10;
  }
  return $sum;
}

// Function to check if a number is a happy number
function isHappyNumber($n)
{
  $slow = $n;
  $fast = $n;
  do
  {
    $slow = sumOfSquares($slow);
    $fast = sumOfSquares(sumOfSquares($fast));
  }
  while ($slow != $fast);

  return $slow == 1;
}

// Replace this value with your desired number
$number = 19;

// Check if the number is a happy number
if (isHappyNumber($number))
{
  echo "$number is a Happy Number.\n";
}
else
{
  echo "$number is not a Happy Number.\n";
}

?>

💻 Testing the Program

To test the program with a different number, replace the value of $number in the code.

Output

19 is a Happy Number.

Run the script to check if the number is a happy number.

🧠 How the Program Works

The program defines a function sumOfSquares to calculate the sum of the squares of digits of a given number.
It then defines a function isHappyNumber that checks whether a given number is a happy number using Floyd's cycle detection algorithm.
The script tests the program with a sample number (in this case, 19).

📏 Between the Given Range

Let's take a look at the php code that checks for Happy Numbers in the specified range.

findHappyNumbers.php

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<?php
// Function to check if a number is happy
function isHappy($num)
{
  while ($num != 1 && $num != 4)
  {
    $sum = 0;
    while ($num)
    {
      $sum += ($num % 10) * ($num % 10);
      $num /= 10;
    }
    $num = $sum;
  }
  return $num == 1;
}

// Function to find and display happy numbers in a given range
function findHappyNumbers($start, $end)
{
  echo "Happy numbers in the range $start to $end:\n";
  for ($i = $start;$i <= $end;++$i)
  {
    if (isHappy($i))
    {
      echo "$i ";
    }
  }
  echo "\n";
}

// Driver program
// Define the range
$start = 1;
$end = 50;

// Call the function to find and display happy numbers
findHappyNumbers($start, $end);

?>

💻 Testing the Program

The provided script checks for happy numbers within the range of 1 to 50. To test with a different range, modify the values of $start and $end in the code.

Output

Happy numbers in the range 1 to 50:
1 7 10 13 19 23 28 31 32 44 49

Run the script to see the happy numbers in the specified range.

🧠 How the Program Works

The program defines a function isHappy that checks if a number is a happy number using the iterative process described earlier.
The function findHappyNumbers iterates through the specified range and prints the happy numbers.

🧐 Understanding the Concept of Happy Number

A happy number is a positive integer defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1, or it loops endlessly in a cycle that does not include 1.

For example, let's take the number 19:

1²+9² = 82
8²+2² = 68
6²+8² = 100
1²+0²+0² = 1

In this case, 19 is a happy number because the process ends with 1.

🎢 Optimizing the Program

While the provided program is effective, there are various ways to optimize and enhance it further. Consider exploring different algorithms or incorporating additional features based on your specific requirements.

Feel free to incorporate and modify this code as needed for your specific use case. Happy coding!