Creating Functions in PHP – A Quick Guide

Learn how to define and use functions in PHP, pass parameters, return values, and follow best practices to write reusable code.

📌 What Are Functions?

Functions are blocks of reusable code that perform specific tasks. In PHP, functions help reduce repetition, organize code, and improve readability.

✍️ Defining a Simple Function

Use the function keyword followed by a name and a pair of parentheses.

<?php
function sayHello() {
  echo "Hello, world!";
}
sayHello();
?>

This outputs Hello, world! when called.

📦 Functions with Parameters

Parameters allow you to pass values to functions.

<?php
function greet($name) {
  echo "Hello, $name!";
}
greet("Alice");
?>

Outputs: Hello, Alice!

🔁 Returning Values from Functions

Use return to send a result back to the caller.

<?php
function add($a, $b) {
  return $a + $b;
}
$result = add(5, 7);
echo $result; // 12
?>

🛠️ Default Parameter Values

Set default values to make parameters optional.

<?php
function greetUser($name = "Guest") {
  echo "Welcome, $name!";
}
greetUser(); // Welcome, Guest!
?>

🔍 Type Hinting

PHP allows you to specify expected types for parameters and return values (PHP 7+).

<?php
function multiply(int $x, int $y): int {
  return $x * $y;
}
echo multiply(3, 4); // 12
?>

👻 Anonymous Functions & Closures

You can create functions without a name and assign them to variables.

<?php
$shout = function($msg) {
  echo strtoupper($msg);
};
$shout("hello"); // HELLO
?>

📌 Variable Scope

Variables inside functions are local by default. Use global to access outside variables.

<?php
$site = "MyBlog";
function showSite() {
  global $site;
  echo $site;
}
showSite();
?>

✅ Best Practices

• Use descriptive names like calculateTotal() or sendEmail()
• Keep functions short and focused on one task
• Return results instead of echoing inside functions (makes testing easier)
• Avoid using global variables inside functions unless absolutely necessary

🌍 Real-World Use Cases

• Form validation
• Database operations
• Formatting and sanitizing input
• Calculations and reports
• Email notifications

Tags: PHP functions, define function PHP, function examples PHP, PHP beginner tutorial

📘 Up next: Learn how to include and organize code across multiple PHP files using include and require.