The abs() function in PHP is used to return the absolute (non-negative) value of a number.

Syntax:

abs(number)

• number: A numeric value. It can be positive, negative, or zero.

What it does:

• If the number is positive, it returns the same number.
• If the number is negative, it returns the positive equivalent.
• If the number is zero, it returns 0.

Examples:

<?php
echo abs(10);     // Output: 10
echo abs(-10);    // Output: 10
echo abs(0);      // Output: 0
echo abs(-5.75);  // Output: 5.75
?>

Use Case Example:

Let's say you want to calculate the difference between two values, and you don’t care about the order.

<?php
$actual = 80;
$expected = 100;
$difference = abs($actual - $expected);

echo "Difference is: $difference";  // Output: Difference is: 20
?>

This ensures that even if $actual is greater than $expected, you still get a positive difference.