How to write redirect rule for a string in url with wildcard?

Suppose I have a few urls like:

http://www.digitalpoint.com/world-is-big.html
http://www.digitalpoint.com/round-world.html
http://www.digitalpoint.com/hello-world.html
etc in which a common string "world" is there.

Now I want that whenever a user go for an url which has the string world in it will ge redirect to another page like
http://www.digitalpoint.com/index.php?id=world.

How to write the redirect rule for this?

 

I am not really sure on how to do this with .htaccess, but if you want, you could do it with php

 

I tried for whole night and finally got it.
it will be

RewriteEngine on
Options +FollowSymLinks
RewriteCond %{HTTP_HOST} ^digitalpoint.com$
RewriteRule ^(.+)(world)(.+)\.html$ "http\:\/\/www\.digitalpoint\.com\/index\.php\?id\=world" [R=301,L]
RewriteRule ^(world)(.+)\.html$ "http\:\/\/www\.digitalpoint\.com\/index\.php\?id\=world" [R=301,L]
RewriteRule ^(.+)(world)\.html$ "http\:\/\/www\.digitalpoint\.com\/index\.php\?id\=world" [R=301,L]

I have written three rules for abouve three urls but I think there is way of writing them all in one rule using the ? wildcard. I haven't tried it coz all of my urls have that particular keyword somewhere in the middle so i just needed the first rule. But i think it will be....

RewriteRule ^((.+)?)(world)((.+)?)\.html$ "http\:\/\/www\.digitalpoint\.com\/index\.php\?id\=world" [R=301,L]