A Simple User Function

 
function foo( ) {
            return  1;
    }

    print foo( );

1.	Create function from string
2.	Declaring a Simple Function
3.	Function printing text on a Web Page
4.	Declaring a Function
5.	A Function Requiring Two Arguments
6.	A Function to Build Query Strings
7.	A function that calculates sales tax
8.	Accessing a Global Variable from Within a Function
9.	Build and then call a function
10.	Call the function
11.	Create a User Function
12.	Defining functions before or after calling them
13.	Creating and calling a function that accepts arguments
14.	Define constant in a function
15.	nesting functions
16.	global key word in a function
17.	Variables Defined Outside Functions Are Inaccessible from Within a Function by Default
18.	Using nested functions

A Simple User Function : Definition « Functions « PHP