Variables Scope in PHP
There are three types of variable scopes in PHP . They are as follows:
1) Local
2) Global
3) Static
Local Scope : When a variable declared inside a function (has a local scope ) and it can only be accessed within that function, the variable is called as local scope variable .
E.g.
<?php
function localvar()
{
$x=6; //local scope variable
echo "Variable x inside function is : $x";
}
localvar();
echo "Variable x outside function is : $x";//generate an error like undefined variable
?>
Output:
Variable x inside function is : 6
Notice: Undefined variable: x
Variable x inside function is :
Global Scope : When a variable declared outside a function (has a global scope) and it can only be accessed outside a function, the variable is called as global scope variable .
E.g.
<?php
$x=10; //global scope
function globalvar()
{
echo "Variable x inside function is : $x";//generate an error like undefined variable
}
globalvar();
echo "Variable x outside function is : $x";
?>
Output:
Notice: Undefined variable x
Variable x inside function is :
Variable x outside function is : 10
Global Keyword : By using global keyword we can access a global variable within a function. Just add or write global keyword before the variables inside the function. As follows,
e.g.
<?php
$x=10; //global scope
function globalvar()
{
global $x;//By using global keyword
echo "Variable x inside function is : $x<br>";
}
globalvar();
echo "Variable x outside function is : $x";
?>
Output :
Variable x inside function is : 10
Variable x outside function is : 10
Static Scope : When a function is executed , all of its variables are deleted. However we want a local variable not to be deleted. We need it for further job. Use the static keyword when you first declared the variable . Then each time the function is called , the variable will still have the information it contained from the last time the function called.
e.g.
<?php
function scopevar (){
static $x=11;
echo $x;
$x++;
}
scopevar ();
echo "<br>";
scopevar();
echo "<br>";
scopevar ();
?>
Output :
11
12
13
In that way we learn variables scope in short .
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