Calculator

A powerful calculator.

How to open

APK: app-debug.apk

Google Play Store: https://play.google.com/store/apps/details?id=com.bx.calculator

Logic

Expression Evaluating Algorithm:

Shunting-yard algorithm, which some modifications for pre-functions, post-functions, implied multiplication and negations.

Reverse Polish Notation

Abstract Syntax Tree

Code

Data types

• CToken

  A token in a mathematical expression. It could be a number, operator, variable, etc.

• CExpression

  An object representing a mathematical expression, an array of tokens.

• CParams

  An object containing parameters for a calculation, including angle units and values for variables.

• CResult

  An object respresenting the result of a calculation. It includes the original expression, calculation parameters and the calculated result. The result does not have to be correct after re-calculating the original expression if the calcuation algorithm has changed.

References

• Shunting-yard algorithm
• Reverse Polish Notation
• Abstract Syntax Tree
• Parsing math expressions
• W3Eval

Screenshots