About

• By using Shunting-yard algorithm rpn can evaluate a mathematics expression, that includes:

  • Multiple digits number (floating point)

  • Opearators (+, -, unary -, unary +, *, /)

  • Parentheses

  Plus:

  • Invalid parentheses check

  • Invalid operators check

Build

• On Linux (Arch Linux), inside the rpn top level directory:

make

Run

./build/rpn

or

make run

TODO

• Optional multi-threads.

• Support unary minus operator.

  • Redesign unary relations?

• Add debugging utilities.

  • Command line args support.

  • Enable/disable debug with command line option or environment variables.

  • Debug level as a flag to enable debugging a specific function.

  • Log file.

• Implicit multiplication

  • 2(3+4)5

  • (1+2)(2+3)

  • Whenever there is no operator, it is multiplication?

• Support function operators (sin, cos, .etc)?

• Support portability.

• A development branch.

What Did I Learn From Writing The rpn

• I learned how to design and construct data type like a struct that can hold both operands (numbers) and operators (operator ids).

• Data type (Node) and Stack are separable.

  • stack.h can be use as a library.

• Yeah, I decided to avoid dynamic memory allocation, it require a lot of (multi-layers) memory management.

  I chose to stick with automatic memory allocation and static memory allocation, they are simple.

• Operation orders in mathematics and in computer are not the same, there is no "standard rule".

  But there might have one: whenever it is ambiguous, just use parentheses.

• Working with mathematics expression, it reinforces my mathematics area a little bit (it was really weak already).