Introduction to PHP Programming

By PHP Catalyst
2007-11-19


Scope of a Variable

By default, most variables in PHP will have only single scope. This single scope is available to the included files as well. For example

In the above example, the variables $a, $b, $c will be available within the included file cal.php as well. But this differs for the variables used inside a function. Let's see this example:

Upon execution of the above code, you will see 'Undefined Variable' notices. This is because, when you use $a, $b and $c variables within the function, they are treated as local variables and hence the value of which is not obtained from the variables used outside of the function. To be able to use these variables, you will have to declare them as global variables inside the function using the global keyword. See the modified example:

Now execute the code and you will see an output. This is because after declaring the variables as global, the variables which are declared outside the function becomes available within the function as well. Note that in our example, the variable $d is still a local variable within the function print_sum().

We hope that the above explanation was clear.

Tutorial Pages:
» What can I do with PHP?
» Popoular Features of PHP
» Basics of PHP
» Variables in PHP
» Data Types in PHP
» Expressions and Operators
» Control Structures in PHP
» Functions in PHP
» Declaring Functions in PHP
» Scope of a Variable
» Built-in Functions in PHP
» Handling Strings in PHP
» Printing Strings in PHP
» String Comparisons in PHP
» Manipulating Strings in PHP
» Arrays in PHP
» Types of Arrays in PHP
» Creating Arrays in PHP
» Array Operations in PHP

Related Tutorials: » Web Database Access from Desktop Applications » CubeCart 3.0 Installation and Configuration » PHP Site Search Made Easy » Installing and Configuring Drupal 6.1 » Desktop Application Development with PHP-GTK » Installing PHP on Windows