Stack-Based Expression Evaluator & Converter (GUI)

A Data Structures & Algorithms (DSA) project implemented in C++ with Qt GUI.
This application converts and evaluates Infix, Postfix, and Prefix expressions using stack data structures implemented via arrays and linked lists.

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🎯 Project Objectives

• Apply stack concepts in a real-world application
• Implement expression conversion and evaluation algorithms
• Practice modular C++ programming
• Build a simple GUI using Qt (signals & slots)

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🧠 Concepts Used

• Stack (Array-based implementation)
• Stack (Linked List-based implementation)
• Infix, Postfix, Prefix expressions
• Expression conversion algorithms
• Expression evaluation
• Exception & error handling
• File handling (history storage)
• Qt GUI (Widgets, Signals & Slots)

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🖥️ Features

• ✅ Convert Infix → Postfix
• ✅ Convert Infix → Prefix
• ✅ Evaluate Postfix expressions
• ✅ Error handling for malformed expressions
• ✅ Expression history displayed in GUI
• ✅ Modular code structure
• ✅ Clean and user-friendly GUI

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🪟 GUI Overview

The application contains:

• Expression input field
• Buttons for:
  • Convert to Postfix
  • Convert to Prefix
  • Evaluate Expression
• Result display field
• History list showing previous operations

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📂 Project Structure