Advanced CLI Calculator in C++

This project is an advanced Command-Line Interface (CLI) calculator implemented in C++. The calculator can evaluate mathematical expressions using infix notation, supporting basic arithmetic operations like addition, subtraction, multiplication, division, and exponentiation. It also handles operator precedence and parentheses.

Features

• Supports the following operators:
  • Addition (+)
  • Subtraction (-)
  • Multiplication (*)
  • Division (/)
  • Exponentiation (^)
• Handles operator precedence (e.g., multiplication and division before addition and subtraction).
• Supports parentheses for grouping expressions.
• Error handling for invalid expressions, including division by zero.

How It Works

1. Tokenization: The input expression is first converted into tokens, separating numbers, operators, and parentheses.

2. Infix to Postfix Conversion: The infix expression (which is human-readable) is converted into postfix notation using the Shunting Yard algorithm. Postfix notation is easier to evaluate programmatically because it doesn't require handling operator precedence.

3. Postfix Evaluation: The postfix expression is then evaluated using a stack-based approach.

Example

For an expression like 12 + 2 - ( 2 + 2 ) * 2, the calculator processes it as follows:

1. Tokenize: Break down the expression into individual components: ["12", "+", "2", "-", "(", "2", "+", "2", ")", "*", "2"].

2. Convert to Postfix: Convert the infix expression to postfix notation: ["12", "2", "+", "2", "2", "+", "2", "*", "-"].

3. Evaluate Postfix: Evaluate the postfix expression to get the result: 8.

Code Structure

• precedence(): Determines the precedence of operators (+, -, *, /, ^).
• applyOp(): Applies the operator to two operands.
• tokenize(): Converts the input string into tokens.
• infixToPostfix(): Converts the tokenized infix expression to postfix notation using the Shunting Yard algorithm.
• evaluatePostfix(): Evaluates the postfix expression to produce a numerical result.
• calculator(): The main function that handles user input and integrates all the above functions.

Getting Started

Prerequisites

To compile and run this program, you'll need:

• A C++ compiler (e.g., clang++, g++)
• A terminal or command prompt

Compilation

1. Clone or download the repository to your local machine.
2. Open your terminal or command prompt and navigate to the directory containing main.cpp.
3. Compile the code using a C++ compiler. For example, using clang++:

# With clang++ compiler
clang++ -std=c++20 main.cpp -o calculator
# or with g++ compiler
g++ main.cpp -o calculator

Running the Program

1. Run the program by executing the compiled file:

./calculator

2. Example program structure

$ ./calculator
Enter a mathematical expression (or type 'exit' to quit): 12 + 2 - (2 + 2) * 2
Result: 8
Enter a mathematical expression (or type 'exit' to quit): exit