This is a calculator I developed depending on a guideline of VidMob Engineering Take Home Exercise.

• Python 3.x should be installed

1. Store all files in calculator.zip at the same location

2. Run calculator.py

3. Working successfully, you can see the below

   ​ Please enter a mathematical expression. Type 'exit' to leave.

4. Input an expression; input 'exit' to end the program

5. Get a calculated value; an error might happen through an input validation

• (clear) Take text or string as input
• (clear) Support positive, negative, and decimal numbers
• (clear) Support +, -, *, and / operations
• (clear) Support parentheses
• (clear) A bit of documentation or help text for how to use this program

• Infix -> Postfix

  Infix Expression: A + B * C + D

  Postfix Expression: A B C * + D +

  Ways to do

  1. Prioritize operators

  2. Suppose parenthesis exists according to the priority of operators

  3. Move operatros back after ")"

  4. Remove parenthesis

     e.g. A + B * C -> (A + ( B * C ) -> A B C * +

> 1 + 2

3.0

> 4*5/2

10.0

> -5+-8--11*2

9.0

> -.32 /.5

-0.64

> (4-2)*3.5

7.0

> 2+-+-4

Syntax Error

> 19 + cinnamon

Invalid Input

• Unittest will be implented
• Handle various errors
• Demo will be added

• "Stack" class will be added and replaced existed stacks
• Variable names are edited to be intuitive and readable