htaccess - add custom rewrite to standard wordpress rewrites - php

Question

i have a wordpress website
i have uploaded some of my php code at the root of my web where wordpress is installed.
i want to open those page directly.
they open if # www.example.com/newcode.php
but i want to open them like www.example.com/newcode (without extension .php)
the problem is when i put some .htacess code to achieve this, all wordpress pages stops and shows error404 not found and if i remove htaccess code then i cant open my own newcode.php page without extension
i tried to put this code in htaccess
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ([^\.]+)$ $1.php [NC,L]
but doesnt work...
this is my wordpress .htaccess (automatically created by wordpress)
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ([^\.]+)$ $1.php [NC,L]
</IfModule>
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
id have more files like newcode.php and some folder in which there are more code files and i want all of them to open like this
i want both wordpress pages as well as my new code page to open without any extension and i cant put newcode.php in seperate folder and make another htaccess for that specific folder

Answer 1

This is documented pretty clearly - especially in this case where you don't even need any regexp knowledge. Simply replace everything before # BEGIN WordPress with:
RewriteEngine On
RewriteRule /newcode /newcode.php [L]