Basics of Working with User-Defined Functions in PHP

Now we will learn how to create our own functions, which can then be used like standard PHP functions.

Let's look at the syntax for creating a custom function.

A function is created using the function command. Next, after a space, comes the function name and parentheses, inside which some code is written:

php<?php
  function func() {
    // some code
  }
?>

Let's look at an example.

Let's make a function named func that, when called, will output an exclamation mark:

php<?php
  function func() {
    echo '!';
  }
?>

Now let's call our function. To do this, you need to write its name and parentheses:

php<?php
  function func() {
    echo '!';
  }
  
  // Call our function:
  func(); // outputs '!'
?>

You can call our function several times - in this case, each function call will perform a new output:

php<?php
  function func() {
    echo '!';
  }
  
  func(); // outputs '!'
  func(); // outputs '!'
  func(); // outputs '!'
?>

Functions can be called before their definition:

php<?php
  func(); // outputs '!'
  
  function func() {
    echo '!';
  }
?>