📱 Postfix-Calc

Postfix-Calc is an Android application built using Java in Android Studio. It is a calculator that uses Infix to Postfix conversion to evaluate mathematical expressions. The calculator provides a simple and intuitive user interface resembling the iOS calculator.

🎯 Features

• Converts infix expressions to postfix notation

• Supports the following operations:

  • ➕ Addition (+)
  • ➖ Subtraction (-)
  • ✖️ Multiplication (×)
  • ➗ Division (÷)
  • 🔢 Modulus (%)
  • 📝 Parentheses (( and ))
  • 🟰 Equals (=) to evaluate the expression
  • 🧹 Clear (AC) and 🔙 Backspace (BACK) operations

• 📱 User-friendly UI designed similar to the iOS calculator

🛠 Technologies Used

• Android Studio: IDE for development

• Java: Programming language

• Stack Data Structure: Used for infix to postfix conversion

🔢 Infix to Postfix Conversion

The conversion follows these precedence rules:

• Operators Precedence:
  • +, - have the lowest precedence
  • ×, ÷, % have higher precedence
  • ( has the highest precedence for parsing purposes
• Operands are directly added to the postfix expression
• Operators are pushed onto a stack according to precedence
• Parentheses are handled separately for grouping expressions

🏗 Code Structure

The core logic for infix to postfix conversion and evaluation is implemented in:

• Infix_To_Postfix1.java:

  • infixPrec(char c): Determines the precedence of operators in the infix expression.
  • stackPrec(char c): Determines the precedence of operators in the stack.
  • rank(char c): Returns the rank of an operator to ensure proper expression evaluation.
  • infix_Postfix(): Converts an infix expression to postfix notation.

• Evaluation1.java:

  • evaluate(float a, float b, char c): Performs arithmetic operations based on the operator.
  • postfixEvaluation(): Evaluates a postfix expression using a stack.
  • Evaluation1(String ans): Initializes the evaluation process by converting infix to postfix.

• MainActivity.java:

  • Handles user input from the calculator UI.
  • Listens for button clicks and updates the display accordingly.
  • Manages parentheses balancing and ensures valid expressions before evaluation.
  • Calls Evaluation1 to compute the result when = is pressed.
  • Implements error handling for invalid expressions.

📥 Installation & Usage

1. Clone the repository:

   git clone https://github.com/Khushi130404/Postfix-Calc.git

2. Open the project in Android Studio.

3. Build and run the application on an Android device or emulator.