AddressBook (C-based Console Contact Manager)

A simple console-based contact management program written in C.
It supports operations like inserting, searching, editing, and deleting contact records, using a Red-Black Tree as the underlying data structure for efficient lookup.
Multithreading has been introduced to improve user experience and responsiveness.

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📌 Features

• Add new contacts
• Search by single or multiple conditions (supports AND / OR)
• Delete contacts by phone number
• Edit contact info (age, name, phone number)
• Save and load contacts to/from a file

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🧱 Project Structure

AddressBook/
├── main.c # Program entry point
├── ui.c / ui.h # User interface logic
├── contact.c / contact.h # Contact struct and related functions
├── contact_store.c / .h # Red-Black Tree-based ContactStore implementation
├── contact_store_internal.h # Internal structures for RBT nodes
├── control.c / control.h # File I/O and record operations
├── benchmark.c # Benchmarking and performance analysis
└── test.h # Unit test declarations

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🧠 Data Structures

• Contact
  A structure holding age, name, and phone number.

• ContactStore (Red-Black Tree)
  Stores all contact entries using a balanced Red-Black Tree to support fast search, insert, and delete operations.

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⚙️ Multithreading Integration

To improve UI responsiveness, selected UI functions have been updated to perform time-consuming I/O tasks in background threads.

✅ Affected Functions

Function	Description
UI_InsertNode	Saves to file on a background thread
UI_DeleteNode	Deletes with animated progress feedback
UI_Search	Performs threaded search with live animation

🔧 Threading APIs Used

• _beginthreadex, WaitForSingleObject, CloseHandle
• Console animation like "Saving...", "Deleting...", "Searching..." shown during operations

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📂 File Format

• Text-based file storage
  • Each contact record is stored in a separate line
  • Save path is passed as a flexible path argument

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🚧 Planned Improvements

• Full rewrite in modern C++ (AddressBook_Cpp)
• Class-based design for Contact, ContactStore
• Smart pointer usage and RAII patterns
• Unit test framework integration
• STL-based containers for data storage