Client-Server Computing - HCF/LCM Game

Project Goal

This project implements a client-server application where two players compete in a game based on Highest Common Factor (HCF) and Lowest Common Multiple (LCM) calculations. The server hosts the game and manages communication between two client players.

Learning Objectives

This project teaches:

• Client-server architecture: Understanding how servers listen for connections and clients communicate with servers
• Network programming: Implementing socket-based communication between processes
• Concurrent programming: Using processes (C++) or threads (Java) to handle multiple clients
• Inter-process communication: Coordinating game state and data exchange between server and clients
• Protocol design: Defining a communication protocol for game flow and data exchange

Game Overview

Two players take turns selecting numbers, and scores are calculated using HCF and LCM:

• Player one's score = HCF of both numbers
• Player two's score = last digit of LCM of both numbers

The game consists of two rounds where players switch roles, and the player with the higher cumulative score wins.

Implementation

• Server: Listens on port 24175, manages game logic, calculates scores, and coordinates between two clients
• Client: Connects to server, sends player ID and number selections, receives game results

See 3341f25prog.pdf for detailed specifications and requirements.

Building the Project

Prerequisites

• C++ compiler (g++ recommended)
• Make utility
• Unix-like operating system (Linux/macOS) for socket programming

Build Instructions

1. Compile both server and client:

   make

2. Compile only the server:

   make server

3. Compile only the client:

   make client

4. Clean compiled executables:

   make clean

This will create two executables:

• server - The game server
• client - The game client

Running the Game

Step 1: Start the Server

Open a terminal and run:

./server

The server will start listening on port 24175 and wait for two clients to connect.

Step 2: Start First Client

Open a second terminal and run:

./client

The first client will be assigned as Player 1. Enter your player ID when prompted.

Step 3: Start Second Client

Open a third terminal and run:

./client

The second client will be assigned as Player 2. Enter your player ID when prompted.

Step 4: Play the Game

Once both clients are connected:

1. Round 1:

   • Player 1 enters a number between 50-99 (must be non-prime)
   • Player 2 enters a number between 60-99 (must be non-prime)
   • Scores are calculated and displayed

2. Round 2:

   • Players switch roles
   • Player 2 enters a number between 50-99 (must be non-prime)
   • Player 1 enters a number between 60-99 (must be non-prime)
   • Final scores are calculated and winner is determined

Game Rules

• Valid numbers for Player 1 (Round 1): 50-99, non-prime
• Valid numbers for Player 2 (Round 1): 60-99, non-prime
• Scoring:
  • Round 1: Player 1 gets HCF, Player 2 gets last digit of LCM
  • Round 2: Player 2 gets HCF, Player 1 gets last digit of LCM
• Penalties:
  • Invalid number (prime or out of range): 0 points for player, 100 points for opponent
  • Duplicate number (same number in both rounds): 0 points for player, 100 points for opponent
  • If both players are invalid: both get 0 points

Example Valid Numbers

Non-prime numbers between 50-99: 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99

File Structure

client-server/
├── server.cpp          # Server implementation
├── client.cpp          # Client implementation
├── utils.h             # Utility function declarations
├── utils.cpp           # Utility function implementations
├── hcf.cpp             # Original HCF function (reference)
├── Makefile            # Build configuration
├── README.md           # This file
└── 3341f25prog.pdf    # Assignment specifications

Troubleshooting

• "Address already in use": Another server may be running on port 24175. Kill it or wait for it to finish.
• Connection refused: Make sure the server is running before starting clients.
• Compilation errors: Ensure you have g++ installed and are using a Unix-like system.