Hello.
In project description you say "mathematical expressions". How complicated expressions?
Four basic operations, sure. Brackets? Functions? Variables? Could you please provide sample input and output?
You say it must be implemented in C. Are third-party libraries are permitted?
You require sockets, but there is no sockets in pure C89/C99 standard. So, can I assume POSIX environment (GNU/Linux, *BSD, Mac)?
Also, you tagged your project with 'C++' tag. Is is mistake?