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Unit 7: Functions

A global keyword also enables you to declare what global variables you want to access, causing Notes
them to be imported into the function’s scope. However, using this keyword is not recommended
for various reasons, such as misbehaving with assigning values by reference, not supporting
unset ( ), and soon.

Here’s a short description of it—but please, don’t use it!
The syntax is

global $var1, $var2, ...;

Adding a global line for the previous example results in the following:
Example: function func()

{

global $var;
$var = 2;

}
$var = 1;

func( );

print $var;
This way of writing the example also prints the number 2.

7.3 Returning Values By Value

You can tell from the previous example that the return statement is used to return values from
functions. The return statement returns values by value, which means that a copy of the value
is created and is returned to the caller of the function.
Example: function get_global_variable_value($name)

{
return $GLOBALS[$name];
}

$num = 10;
$value = get_global_variable_value(“num”);

print $value;
This code prints the number 10. However, making changes to $value before the print statement
only affects $value and not the global variable $num. This is because its value was returned by
the get_global_variable_value ( ) by value and not by reference.

7.4 Returning Values By Reference

PHP also allows you to return variables by reference. This means that you’re not returning a
copy to the variable, but you’re returning the address of your variable instead, which enables

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