dynamic functions

[eluser]Unknown[/eluser]
Hi there.. im new to code igniter.. started it about 3hours ago. and im in the middle of transforming my site to use CI framework. and im wondering how to go about this.

I have several users who are members of my site and part of the development team.
if you go to
about.php?u= {their username} it brings up a little bio
so how would i make it so that if they go to
about/{username}

i know i can go to about.php and make a function for each of their usernames and that will work, but i was hoping that there is another way to do it.

im sure this has been addressed before and its probably somewhere on the wiki or the forum but couldnt find it. Any help is greatly appreciated.