Scientific-CLI-Engine-and-Expression-Parser

A C++ command-line calculator and expression parser

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Scientific CLI Engine and Expression Parser

A C++ command-line calculator and expression parser designed to process arithmetic expressions, variables, parentheses, and calculation history. The project focuses on parsing logic, operator precedence, stacks, queues, tokenization, and file persistence.

Project Status

Core expression parsing and calculator functionality is implemented. Some features shown in the help screen are still planned or require refinement.

Feature Status

Implemented — Working

  • Command-line calculator interface
  • Addition, subtraction, multiplication, and division
  • Parentheses
  • Operator precedence
  • Expression tokenization
  • Basic decimal-number parsing
  • Unary positive/negative number handling
  • Variables from a to z
  • Variable assignment
  • Calculation history
  • History persistence using CHistory.txt
  • Help command
  • Clear command
  • Exit command
  • Invalid-expression detection
  • C++ STL containers including map, stack, deque, and vector

Partially Implemented / Needs Refinement

  • Expression evaluation — The parser/evaluator is implemented, but the current result assignment contains a code-level issue that can cause the displayed result to remain incorrect.
  • Error handling — Invalid expressions are detected, but edge cases such as division by zero need stronger handling.
  • Variable parsing — Basic variables work, but the parser can be improved for more complex expressions and assignments.

Planned — Coming Soon

The following features are not currently implemented or need to be completed:

  • Scientific functions such as sin(), cos(), and log().
  • More complete scientific operations.
  • Stronger division-by-zero protection.
  • Improved expression grammar and parser validation.
  • Better result/error reporting.
  • Expanded variable expressions.
  • Unit and automated tests.
  • Cleaner parser architecture.

How the Parser Works

User Expression
      │
      ▼
Text Normalization
      │
      ▼
Tokenization
      │
      ▼
Operator / Operand Analysis
      │
      ▼
Postfix / Polish-Notation Processing
      │
      ▼
Expression Evaluation
      │
      ▼
Result + History File

Example Expressions

5 + 2 * 3
(4 + 6) / 2
x = 5
x + 10

Available Commands

Command Purpose
help Display the help screen
history Display saved calculation history
clear Clear the console
exit Exit the application

Technologies & Concepts

  • C++
  • Standard Template Library (STL)
  • Expression parsing
  • Tokenization
  • Operator precedence
  • Stack-based processing
  • File I/O
  • Object-oriented programming

Project Structure

Scientific CLI Engine and Expression Parser/
├── Scientific CLI Engine and Expression Parser.cpp
├── Scientific CLI Engine and Expression Parser.sln
├── Scientific CLI Engine and Expression Parser.vcxproj
├── CHistory.txt
└── README.md

Getting Started

  1. Open the .sln file in Visual Studio.
  2. Build the project using the available C++ configuration.
  3. Run the executable.
  4. Enter an expression or one of the supported commands.

Learning Objectives

This project demonstrates practical work with:

  • Lexical/token-level parsing.
  • Operator precedence.
  • Stack and queue based algorithms.
  • Expression evaluation.
  • Variables and state management.
  • File persistence.
  • Console application design.

Roadmap

The next updates will focus on completing scientific functions, improving parser reliability, strengthening error handling, and making the evaluation engine more robust.

Author

Aseelcoding

Built With

  • and-calculation-history.-the-project-focuses-on-parsing-logic
  • c++
  • operator-precedence
  • parentheses
  • queues
  • stacks
  • tokenization
  • variables
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