add/remove software

[Erik Schmidt]

I am trying to install some software, using the add/remove tool under
applications

every time I select a piece of software for installation, it says that I
have to remove conflicting software before I can install this piece of
software

WHAT CONFLICTING SOFTWARE!?!?!?!?

how do I find out what software is conflicting?

also, I am trying to compile c/c++ code on my machine, but every time a
type cc on a simple .c hello world program, it says "stdio.h is not
found"

any help appreciated

I apologize if this is the incorrect list to post this question

TIA