PHP Include and Include_once

What will be the output of following PHP code snippet?

<?php
$i=0;
include_once( "inc.php");
echo "$i";
include( "inc.php");
echo "$i";
include_once( "inc.php");
echo "$i";
include( "inc.php");
echo "$i";
?>

Content of "inc.php" is given below..

<?php
$i++;
echo "Included :: $i";
?>

Answer ::
---------------
Included :: 1
1
Included :: 2
2
2
Included :: 3
3

Discussion ::
-------------
The first "include_once()" includes the file once which increments the value of $i to 1. Hence the first output is shown from first inclusion of inc.php.

Next "include()" statement again includes the inc.php which increments the $i to 2 and the output follows.

Next "include_once()"  does not include the "inc.php" as it was previously included... Hence the old value of $i [2] is retained.

The last "include" again includes the "inc.php" and hence increments the $i again to make it to 3.

AGain check the output of the following code snippet

<?php
$i=0;
include( "inc.php");
echo "$i";
include_once( "inc.php");
echo "$i";
?>

The output ::
---------------
Included :: 1
1
1

Discussion ::
---------------
The first "include()" includes the file "inc.php" which increments the value of $i to 1 and prints the  first line as shown in the output above.
Next "include_once()" does not include the file again ... hence the last value of $i (1) is retained.