What is Variable Scope in PHP?
The variable scope defines the visibility of variables in PHP programs. In PHP there are three variable scopes. These are given below:
(i) Local Scope
(ii) Global Scope
(iii) Static Scope
What is the Local Variable Scope in PHP?
In PHP, when a variable is declared within a function, that variable will contain local scope. Local variable will be accessed and visible only within that function where that will be declared.
Now we will write a program on the local scope of a variable:
In this program, we will define a function f1. Within the function body, there is a local variable $a with an initialized string "welcome" here, and we will try to access that variable outside the function.
<html>
<body>
<?php
function f1()
{
$a="welcome"; //$a variable has a local scope
echo $a;
}
f1(); //function calling
echo $a; //error beacuse local variable is accessing outside the function
?>
</body>
</html>
Output
welcome
E_NOTICE : type 8 -- Undefined variable: a -- at line 10
In the above program, the variable $a has a local scope. After executing the program, there will be an error, because variable $a is accessing outside the function.
Here is a PHP program using a local variable within a function with an initialized value.
In this program, we will use a user-defined function f1, and we will declare a local variable $a with initialized to 5 inside the function then we call the function for three times:
<html>
<body>
<?php
function f1()
{
$a=5; //local scope
$a=$a+1; //increasing value
echo $a."<br>";
}
f1(); //function calling
f1(); //function calling
f1(); //function calling
?>
</body>
</html>
Output
6
6
6
Here function is calling for three times. Local variable will be initialized for every time for each calling of a function(where the local variable is declared). So the outputs are 6,6 and 6.