? PHP Function with Default Parameters

? Quick Overview

PHP allows functions to define default values for parameters. If a value is not provided during a function call, PHP automatically uses the predefined default value.

? Key Concepts

• Default parameters make functions flexible
• Optional arguments reduce repetitive code
• Defaults are overridden when values are passed

? Syntax / Theory

// Function syntax with default parameters
function functionName($param1 = defaultValue1, $param2 = defaultValue2) {
return $result;
}

? Code Example 1: Single Default Parameter

// Function with a default name parameter
<?php
function greet($name = "Guest") {
return "Hello, $name!";
}

echo greet();
echo greet("Alice");
?>

? Code Example 2: Multiple Default Parameters

// Function with multiple optional parameters
<?php
function calculate($a, $b = 10, $c = 5) {
return $a + $b + $c;
}

echo calculate(5);
echo calculate(5, 2);
echo calculate(5, 2, 1);
?>

? Code Example 3: Required + Default Parameters

// Required parameter followed by default parameter
<?php
function order($item, $quantity = 1) {
return "Order: $quantity $item(s)";
}

echo order("Book");
echo order("Pen", 3);
?>

? Live Output / Explanation

? Interactive Example

Try modifying default values and observe how output changes when arguments are omitted or passed.

? Use Cases

• User greetings with optional names
• Calculations with default tax or discount rates
• Reusable utility functions