Functions — Built-in & User-defined

Functions group reusable code. Define with function name() { }. Pass parameters and use return to send a value back.

User-defined functions

Functions group reusable code. Define with function name() { }. Pass parameters and use return to send a value back.

Real-life example: A function is a recipe card — write it once, cook the dish whenever you need it.

Basic function

<?php
function greet(string $name): string {
  return "Hello, $name!";
}

echo greet("Asha");

function add(int $a, int $b): int {
  return $a + $b;
}
echo add(3, 5); // 8
?>

Default parameters and type hints

Parameters can have default values. PHP 7+ supports scalar type hints and return types for safer code.

Real-life example: Default parameters are a coffee shop asking "regular milk?" — you only speak up when you want something different.

Defaults and types

<?php
function calculateDiscount(float $price, float $percent = 10): float {
  return $price - ($price * $percent / 100);
}

echo calculateDiscount(2000);      // 10% default
echo calculateDiscount(2000, 20);    // 20%
?>

Variable scope

Variables inside a function are local. Use global $name inside a function or pass values as arguments. Avoid global when possible.

Real-life example: Local scope is a private diary in your room. Global is a family notice board everyone can read.

Local vs global

<?php
$site = "Rishtaara";

function showSite(): void {
  global $site; // prefer passing as parameter instead
  echo $site;
}
showSite();
?>