📒 Address Book Management System (C)

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📌 Overview

The Address Book Management System is a console-based application developed in C to manage contact details efficiently. It supports creating, searching, editing, deleting, and listing contacts with strong input validation and persistent storage using file handling.

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🚀 Features

• ➕ Add new contacts
• 🔍 Search contacts (by Name / Phone / Email)
• ✏️ Edit existing contacts
• ❌ Delete contacts
• 📋 Display all contacts in table format
• 💾 Save contacts to file (contacts.txt)
• 📂 Load contacts automatically on startup
• 🔐 Strong input validation:
  • Name → only alphabets & spaces
  • Phone → 10 digits, starts with 6–9
  • Email →
    • must contain @
    • must end with .com
    • no uppercase letters
    • domain only alphabets
• 🚫 Duplicate prevention (Phone & Email)
• 🔁 Retry system (3 attempts for invalid input)

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🛠️ Tech Stack

• Language: C
• Concepts Used:
  • Structures
  • Arrays
  • Functions
  • Strings
  • File Handling
  • Recursion & Iteration
  • Input Validation

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📂 Project Structure

├── main.c        → Menu-driven interface (entry point)
├── contact.c     → Core logic (create, search, edit, delete)
├── contact.h     → Structure definitions & function declarations
├── file.c        → File handling (save & load contacts)
├── file.h        → File function declarations
├── contacts.txt  → Stored contact data (auto-created)

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⚙️ How It Works

1. Loads existing contacts from file at startup.
2. Displays a menu-driven interface.
3. Validates all user inputs:
   • Name → alphabets & spaces only
   • Phone → 10 digits, starts with 6–9, unique
   • Email → valid format, unique, ends with .com
4. Stores data using structures and arrays.
5. Saves all contacts to file before exiting.

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🔐 Validation Highlights

• Maximum 3 retry attempts for invalid inputs
• Email validation:
  • Must contain @
  • Must end with .com
  • Domain contains only alphabets
• Prevents duplicate entries
• Safe input handling to avoid crashes

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📸 Screenshots

Menu

Create Contact

List Contacts

🧠 Key Learnings

• Modular programming using multiple files
• Debugging segmentation faults and logical errors
• Real-world input validation techniques
• File handling (fopen, fprintf, fscanf)
• Efficient data management using structures

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📈 Future Enhancements

• Support for multiple domains (.org, .net)
• Sorting contacts (Name / Phone)
• Partial search (substring match)
• Develop a GUI version using Qt framework (C/C++) for better user interaction
• Export contacts to CSV / Excel

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🙌 Author

Hariharan R
🎓 2025 Graduate | Electronics and Communication Engineering
🔧 Aspiring Embedded Systems Engineer
💻 Strong in C Programming, Problem Solving & Input Validation Logic
⚙️ Interested in Embedded Systems, Microcontrollers & Low-Level Development

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🌟 Support

If you like this project:

⭐ Star this repository
🍴 Fork and improve it
📢 Share with others

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📬 Contact

• 📧 Email: hariharanrbe@gmail.com
• 💼 LinkedIn: https://www.linkedin.com/in/hariharanrbe/

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🏷️ Tags

C Programming File Handling Data Structures Console Application Projects