YACC (Yet Another Calc Compiler)

The year is 1973. You find yourself having just been hired by the US Department of Defense to work on the next greatest missile system. You can't believe you actually landed the job!

On your first day, the program manager shows you the ropes. You can't help but be excited, Version 4 Unix has just been released and you've been told that they have it running on their new PDP11's. As the manager leaves you at your desk, they briefly mention that there is no tolerance for miss calculations. You quickly reply with a sharp ofcourse! It then dawns on you, the calculator program on Unix, dc, is in postfix notation! A wave of panic washes over you as recall how mistake prone you are with this notation. You simply can't do your job with dc.

You suddenly think to yourself, "I know how to fix it! Why not write another calculator program for Unix, but instead in infix notation? I'll call it bc."

Next Step

Right now, in the terminal emulator to the right, there is a stub program called bc that has been defined. Try running:

$ bc

If you try executing an expression, such as:

$ 2 + 2

it will print out an error message. Not to fear, we will return here once we've implementing bc. Until then, lets get started with (1) Lexical Analysis.