PHP Variable Scope
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PHP Variable Scope
Variable scope in PHP refers to the area of the script where a variable is visible and accessible. PHP has three types of variable scopes:
- Global scope: A variable declared outside a function or class has a global scope and can be accessed from anywhere in the script, including inside functions and classes.
$name = "John"; // global variable
function print_name() {
global $name;
echo $name; // output: John
}
print_name();
- Local scope: A variable declared inside a function or method has a local scope and can only be accessed within that function or method.
function print_name() {
$name = "John"; // local variable
echo $name; // output: John
}
print_name();
echo $name; // throws an error: undefined variable $name
- Static scope: A variable declared inside a function or method with the static keyword has a static scope and retains its value between function calls.
function increment() {
static $count = 0; // static variable
$count++;
echo $count;
}
increment(); // output: 1
increment(); // output: 2
increment(); // output: 3
It’s important to note that when a function or method is called, PHP creates a new local scope for it. Any variables declared inside the function or method are destroyed when the function or method returns. To access a global variable inside a function or method, you need to use the global keyword to import it into the local scope.
It’s good practice to limit the use of global variables in your code as they can make your code harder to read, maintain, and debug. Instead, try to use local variables whenever possible and pass values between functions and methods using arguments and return values.
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