Variable scope (global, local, static)

In PHP, the scope of a variable determines where you can access or use that variable in your program. There are mainly 3 types of variable scope in PHP:

1. Local Scope
2. Global Scope
3. Static Scope

1. Local Scope:

• A variable declared inside a function is local to that function.
• You cannot access it outside the function.

Example:

<?php
function testLocal() {
    $x = 10; // Local variable
    echo "Inside function: x = $x <br>";
}

testLocal();
echo "Outside function: x = $x"; // Error: x not defined outside
?>

Explanation:

• $x only exists inside the function.
• Output:
  • Inside function: x = 10
  • Outside function: x =

2. Global Scope:

• A variable declared outside a function has global scope.
• To access it inside a function, you must use the global keyword.

Example:

<?php
$x = 20; // Global variable

function testGlobal() {
    global $x;  // Import global variable into function
    echo "Inside function: x = $x <br>";
}

testGlobal();
echo "Outside function: x = $x <br>";
?>

Explanation:

• Without the global keyword, $x inside the function would not work.
• Output:
  • Inside function: x = 20
  • Outside function: x = 20

Another Way:

• PHP offers a unique superglobal array named $GLOBALS[] that allows access to global variables within functions.

Example:

<?php
$a = 5;
$b = 10;

function sum() {
    $GLOBALS['c'] = $GLOBALS['a'] + $GLOBALS['b'];
}

sum();
echo "The sum is: " . $c;
?>

Explanation:

• Output: The sum is: 15

3. Static Scope:

• Normally, when a function ends, local variables are destroyed.
• If you declare a variable as static, it will keep its value between function calls.

Example:

<?php
function counter() {
    static $count = 0; // Static variable
    $count++;
    echo "Count = $count <br>";
}

counter();
counter();
counter();
?>

Explanation:

• Output:
  • Count = 1
  • Count = 2
  • Count = 3