Functions (Built-in & User-defined)
Functions in PHP are blocks of code
designed to perform a specific task. They help make code reusable, organized,
and easier to maintain. PHP provides built-in functions for common
tasks, and also allows you to create your own user-defined functions.
Built-in
Functions
PHP has hundreds of built-in
functions that perform predefined operations such as string manipulation,
mathematical calculations, and array handling.
Example (Built-in Functions):
<?php
//
String length
echo
strlen("Hello World"); // Outputs: 11
//
Find maximum value in an array
echo
max(10, 20, 30); // Outputs: 30
//
Convert string to uppercase
echo
strtoupper("php is awesome"); // Outputs: PHP IS AWESOME
?>
User-defined
Functions
You can create your own functions to
execute code whenever needed. This helps reduce repetition and makes programs
easier to read.
Syntax:
function
functionName($parameter1, $parameter2) {
// Code to be executed
return $result;
}
Example (User-defined Function):
<?php
function
greet($name) {
return "Hello, " . $name . "!";
}
echo
greet("John"); // Outputs: Hello, John!
?>
Functions
with Default Parameters
If a function parameter has a
default value, it can be omitted when calling the function.
Example:
<?php
function
welcome($name = "Guest") {
return "Welcome, " . $name;
}
echo
welcome(); // Outputs: Welcome, Guest
echo
welcome("Sara"); // Outputs: Welcome, Sara
?>
Returning
Values
Functions can return values to be
used later in the program.
Example:
<?php
function
add($a, $b) {
return $a + $b;
}
$result
= add(5, 10);
echo
$result; // Outputs: 15
?>