User Defined Functions in PHP

<?php

//Function Without Argument
Add();
function Add()
{
$a=5;
$b=6;
$c=$a+$b;
echo $c;
}

echo "<br/>";

//Function With Argument
Add1(5,6);
function Add1($a,$b)
{
$c=$a+$b;
echo $c;
}

echo "<br/>";

//Returning Value From Function
echo Add2();
function Add2()
{
$a=5;
$b=6;
$c=$a+$b;
return ($c);
}
?>

Output :-