Variable Scope

$a = 1;
function Test(){ /* reference to local scope variable*/
        echo "\$a - Value (local scope) : $a \n";
}
Test();

$a = 1;   
$b = 1;
function Test2(){
        global $a, $b;
        $b = $a + $b;
}
Test2();    
echo "Globally changed \$b $b<br>\n";

// Useless Function it does nothing
function Test3(){
        $a = 0;
        echo $a;
        $a++;
}
// This function allows us to increment a counter
function Test4(){
        static $a = 0;
        echo $a;
        $a++;
}
Test3();Test3();Test3();   
echo ";";
Test4();Test4();Test4();

echo "Variable variable<br />\n";
$a = "hello"; // How to set a normal variable
$$a = "world";
echo "$a ${$a}";
echo "$a $hello"; // Produce exactly the same output