Defining Functions

There are already many functions built into PHP. However, you can define your own and organize your code into functions. To define your own functions, start out with the function statement:

function some_function([arguments]) { code to execute; }

The brackets ([ ]) mean optional. The code could also be written with optional_ arguments in place of [arguments]. The function keyword is followed by the function name. Function names abide by the same rules as other named objects, such as variables, in PHP. A pair of parentheses (()) must come next. If your function has parameters, they're specified within the parentheses. Finally, the code to execute is listed between curly braces, as seen in the previous code example.

You can define functions anywhere in your code and call them from virtually anywhere. The scope rules are described in Chapter 3. As you may remember, the scope of a variable is the context within which it's defined. For the most part, all PHP variables have only a single scope. A single scope spans included and required files as well. The function is defined on the same file or included in an include file. Functions can have parameters and return values that allow you to reuse code.

To create your own function that simply displays a different hello message, you would write:

echo ("Hello from function-land!");

which displays:

Hello from function-land!

The hi function doesn't take any parameters, so you don't list anything between the parentheses. Now that you've defined a simple function, let's mix in some parameters.

Was this article helpful?

0 0

Post a comment