PHP Exercises: Check if two numbers are approximately equal to each other

Last update on April 19 2025 11:49:10 (UTC/GMT +8 hours)

94. Approximately Equal Number Check

Write a PHP program to check if two numbers are approximately equal to each other.

Note: Use abs() to compare the absolute difference of the two values to epsilon. Omit the third parameter, epsilon, to use a default value of 0.001.

Sample Solution:

PHP Code:

<?php
// Licence: https://bit.ly/2CFA5XY

// Function definition for 'approximatelyEqual' that takes two numbers and an optional epsilon value as parameters
function approximatelyEqual($number1, $number2, $epsilon = 0.001)
{
    // Check if the absolute difference between the numbers is less than the epsilon value
    if (abs($number1 - $number2) < $epsilon)
        // If approximately equal, return 1 (true)
        return 1;
    else
        // If not approximately equal, return 0 (false)
        return 0;
}

// Call 'approximatelyEqual' with two numbers and display the result using 'print_r'
print_r(approximatelyEqual(10.0, 10.00001));

// Display a newline
echo("\n");

// Call 'approximatelyEqual' with two different numbers and display the result using 'print_r'
print_r(approximatelyEqual(10.0, 10.01));

?>

Explanation:

Function Definition:

The approximatelyEqual function takes three parameters:

$number1: the first number to compare.
$number2: the second number to compare.
$epsilon: an optional precision threshold, defaulted to 0.001.

Check Approximate Equality:

The function calculates the absolute difference between $number1 and $number2 using abs($number1 - $number2).
If this difference is less than $epsilon, the numbers are considered approximately equal.

Return Result:

If the numbers are approximately equal, the function returns 1 (true).
If not, it returns 0 (false).

Function Calls and Output:

approximatelyEqual(10.0, 10.00001) checks if 10.0 and 10.00001 are approximately equal within 0.001. Result: 1 (true).
approximatelyEqual(10.0, 10.01) checks if 10.0 and 10.01 are approximately equal within 0.001. Result: 0 (false).

Output:

1
0

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to compare two floating point numbers and return true if their difference is within a small epsilon value.
Write a PHP function to determine if two numbers are nearly equal by checking if their absolute difference is less than 0.001.
Write a PHP script to check for approximate equality between two decimal numbers using a custom tolerance.
Write a PHP script to evaluate if two numbers are approximately equal by comparing their difference to a default epsilon value.

PHP Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Write a PHP program to sort a collection of given arrays or objects by key.
Next: Write a PHP program to check if a given string starts with a given substring.