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
?>