[PHP] how can I do this !!

[Alawi]

i have txt file have this words 

----------
bla bla bla 

[phpcode]
<?
echo 'hello word';
?>
[/phpcode]

bla bla bla
-----------

now I want to convert the code that are between [phpcode] and [/phpcode] to colorized 
code ..
How I can do that