Option in Unix for line by line execution

I am doing unix programming in c. I have used semaphores for doing some problems like producer consumer problem the thing that i found difficult it that unlike in C++ or C, the debugging in this is very difficult as there is no way to execute the program line by line. Can sombody tell me if there is any option in unix for line by line execution..?

I thnk u can do it using gcc or gdb.
They are debuggers..I am not sure what are the exact commands
Man gdb mite help