C从命令提示符中获取参数作为条件

I'm completely new to C...well sort of. i kind know c++. I'm trying to run a multi-threated program for my assignment, and one of the requirements was to have the user input his commands on the command prompt. Essentially what i'm asking is, how can i set up int main so that it can constantly take inputs from the command prompt(so i can start new threads) without stopping, and how to make comparisons such as if the user presses 'E' do this, if he presses F do that and so on. I'm guessing that the argc doesnt matter at all because i don't know how many commands the user is going to enter. What would be the best way to go on about thisI'm completely new to C...well sort of. i kind