How to hide .php extension in .htaccess [duplicate]

Possible Duplicate:
Remove .php extension with .htaccess

I'm trying to hide the .php file extension but for some reason can't get it to work. My latest attempt was the following:

<IfModule mod_rewrite.c>
   RewriteEngine on
   RewriteRule ^folder/([a-zA-Z_\-0-9]+)/?$ /folder/$1.php
</IfModule>

I have tried many different variances of code I have found online but still no luck. The .htaccess file is placed within the root directory.

I've used this:

RewriteEngine On

# Unless directory, remove trailing slash
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/]+)/$ http://example.com/folder/$1 [R=301,L]

# Redirect external .php requests to extensionless URL
RewriteCond %{THE_REQUEST} ^(.+)\.php([#?][^\ ]*)?\ HTTP/
RewriteRule ^(.+)\.php$ http://example.com/folder/$1 [R=301,L]

# Resolve .php file for extensionless PHP URLs
RewriteRule ^([^/.]+)$ $1.php [L]

See also: this question

The other option for using PHP scripts sans extension is

Options +MultiViews

Or even just following in the directories .htaccess:

DefaultType application/x-httpd-php

The latter allows having all filenames without extension script being treated as PHP scripts. While MultiViews makes the webserver look for alternatives, when just the basename is provided (there's a performance hit with that however).