Codes along with relevant comments always get more help!

Does that mean anything?

You can do that with the help of multi threading in C++ and Java. In C, no such feature exists. Although, some libraries for C might be supporting multi threading. I'm not sure.

And one more...

What is that?

Use code tags & re-post the code along with the errors you are getting..

What nonsense code have you submitted?! I fully agree with Ancient Dragon.

Atleast show your code (efforts) & specify where you are stuck up. You are expecting that someone will write the entire code for you. You've not even specified what your specific problem is about.

The error implies that there is some reference to main inside the functions in the file you are trying to compile. As you have not defined main, it will not compile. Try to put the file here so that...