What would be the general structure of a App/Project based in C Programming language. libs, includes, header files. etc etc.
What would be the class structure. (in OOps) need to be scalable and other features. Something like main.cpp main.h
does any one have any good links or images or pdf?
For the directory layout/class structure I suggest reading this
http://www.javapractices.com/topic/TopicAction.do?Id=205
The link talks about Java but it applies to any Language (even non- OOP)
You might also find this interesting
http://www.gnu.org/prep/standards/html_node/index.html
What you could do is find an open-source project in the same domain and study their project structure and adapt it as needed.
I guess there are no common guidelines (at least, i've heard of none). Every company seem to have its own practices and recommendations. You may only rely on yourself and do whatever suits your current needs, i think.
Here's a link to the Google C++ Style Guide, if you haven't seen it already: https://google.github.io/styleguide/cppguide.html (they've got lots of ideas there, but i don't accept some of them, so it is a matter of choice)
Here's some other random guideline: http://geosoft.no/development/cppstyle.html
I guess you may take a look at those, but there is no general rule of thumb. Everything depends on your exact task.
Create individual libraries according to the functionality,make single include for all header files If it is C use .h or If it is C++ use .hpp format .then have single main file followed make to build all the libraries
OOPS will follows Main.cpp &Main.hpp format
Most of the projects follow a single hierarchy as follows: