please help with this htaccess code

this is my htaccess code.

Options +FollowSymLinks
Options +Indexes

RewriteEngine on
RewriteCond %{HTTP_HOST} ^www\.(([a-z0-9_]+\.)?couponcoder\.in)$ [NC]
RewriteRule .? http://%1%{REQUEST_URI} [R=301,L]

RewriteRule ^admin$ Admin/index.php?qstr=$1 [L]
RewriteRule ^(.*)/$ index.php?qstr=$1 [L]

ErrorDocument 404 /404.php 

Code (markup):

I want to remove the slash at URL end
from

http://couponcoder.in/ZOVI.com/

Code (markup):

to

http://couponcoder.in/ZOVI.com

Code (markup):

can anybody help to fix this?

 

RewriteCond %{HTTP_HOST} !^\.yourdomain\.com$ [NC]
RewriteRule ^(.+)/$ http://%{HTTP_HOST}/$1 [R=301,L] 

Code (markup):

 

try this..

RewriteRule ^(.*)$ index.php?qstr=$1 [L]

Code (markup):

are you trying to redirect with slash to without slash?

 

This code is working.

but its not displaying 404 for invalid URL,

I mean site loads correctly for http://couponcoder.in/Letsbuy.com
and its not showing 404 for invalid URL http://couponcoder.in/Letsb (invalid) its displaying homepage for invalid URL