This is a simple expression interpreter.
Use the command
make to build and
make clean to delete object files.
make run to run the interpreter (must be built before).
You can input any arithmetic expression such as:
(3 + 5) / 6 - 7 * 8 / 99 (((587))) (1 + 2) * (3 + 4)
Note that this interpreter can only support arithmetic expression of this Backus-Naur Form：
e: expression t: term f: factor e => e + t | e - t | t t => t * f | t / f | f f => x | (e) x => number | id
Of course, you can also use variables and assignment statements like this:
a = 114 b = 514 c = a * b - a / b
Finally, you can input
$ to exit.