Programming Smart Functions Using Php & Php 7 - Udemy

The real power of PHP comes from its functions; it has more than 1000 built-in functions.

PHP User Defined Functions

Besides the built-in PHP functions, we can create our own functions.

A function is a block of statements that can be used repeatedly in a program.

A function will not execute immediately when a page loads.

A function will be executed by a call to the function.

Create a User Defined Function in PHP

A user-defined function declaration starts with the word function:

Syntax

function functionName() {
code to be executed;
}

Note: A function name can start with a letter or underscore (not a number).

Tip: Give the function a name that reflects what the function does!

Function names are NOT case-sensitive.

In the example below, we create a function named "writeMsg()". The opening curly brace ( { ) indicates the beginning of the function code and the closing curly brace ( } ) indicates the end of the function. The function outputs "Hello world!". To call the function, just write its name:

Example

<?php
function writeMsg() {
echo "Hello world!";
}

writeMsg(); // call the function
?>