url link with %20

[system]

hey, I have created so many php file, but I forgot to change the file name without space.
so, my link will show %20
lets say: www.happy.com/I%20am%20happy

how to change it to www.happy.com/I_am_happy
replace %20 to _

what php code should I use to do this action?
where to insert the code?

Thanks

[astonecipher]

what php code should I use to do this action?
where to insert the code?

Let’s go with NONE. Go through the files and change the names AND THEN use find and replace to change the links. There is no code to magically change the file names that you created, at least not in PHP.