Building C# Web and Console Applications: A Hands-On Guide with a Guessing Game

Introduction

C# is a versatile programming language widely used for developing various types of applications, including web and console applications. The .NET framework and .NET Core provide robust environments for building scalable, high-performance applications.

This guide outlines the steps for creating a C# web application using ASP.NET Core and a C# console application using .NET.

As part of this tutorial, we will build a simple Guessing Game for both console and web environments. This will demonstrate how to implement user interaction, logic processing, and UI handling in different application types.

---

1. Creating a C# Console Application

A console application is a simple, lightweight program that runs in a command-line interface. It is typically used for utilities, automation scripts, or testing.

Prerequisites

• Install .NET SDK from Microsoft
• Use an IDE such as Visual Studio, Visual Studio Code, or JetBrains Rider

Steps to Create a Console Application

Step 1: Open Command Prompt or Terminal

Run the following command to create a new console application:

dotnet new console -n MyConsoleApp

Step 2: Navigate to the Project Directory

cd MyConsoleApp

Step 3: Open and Modify Program.cs

We will implement a simple guessing game where the user must guess a randomly generated number.

using System;

class GuessingGame
{
    static void Main()
    {
        Random random = new Random();
        int numberToGuess = random.Next(1, 101);
        int userGuess = 0;
        int attempts = 0;

        Console.WriteLine("Welcome to the Guessing Game!");
        Console.WriteLine("Try to guess the number between 1 and 100.");

        while (userGuess != numberToGuess)
        {
            Console.Write("Enter your guess: ");
            string input = Console.ReadLine();

            // Validate input
            if (!int.TryParse(input, out userGuess) || userGuess < 1 || userGuess > 100)
            {
                Console.WriteLine("Invalid input. Please enter a number between 1 and 100.");
                continue;
            }

            attempts++;

            if (userGuess < numberToGuess)
                Console.WriteLine("Too low! Try again.");
            else if (userGuess > numberToGuess)
                Console.WriteLine("Too high! Try again.");
            else
                Console.WriteLine($"Congratulations! You guessed it right in {attempts} attempts.");
        }
    }
}

Step 4: Build and Run the Application

Before running the modified code, build the application using:

dotnet build

Then run the application:

dotnet run

2 Creating a C# Web Application using ASP.NET Core

A web application is a more complex system that runs on a web server and interacts with users through a web browser.

Prerequisites

• Install the latest .NET SDK
• Install Visual Studio (with ASP.NET and Web Development workload)
• Basic knowledge of HTML, CSS, and JavaScript

Steps to Create a Web Application

Step 1: Open Visual Studio and create a new project.

dotnet new webapp -n MyWebApp

Step 2: Navigate to the Project Directory

cd MyWebApp

Step 3: Open Program.cs and Modify It

We will implement a simple web-based guessing game using ASP.NET Core Razor Pages.

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Hosting;
using System;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.UseHttpsRedirection();

// Generate a random number to guess
int numberToGuess = new Random().Next(1, 101);
int attempts = 0;

// Serve the game page and process guesses
app.Map("/", async context =>
{
    string resultMessage = ""; // This will hold feedback messages

    // Only process form data if it's a POST request
    if (context.Request.Method == "POST")
    {
        var form = await context.Request.ReadFormAsync();
        string guessInput = form["userGuess"];

        if (!string.IsNullOrEmpty(guessInput) && int.TryParse(guessInput, out int userGuess))
        {
            attempts++;

            if (userGuess < 1 || userGuess > 100)
                resultMessage = "<p style='color: red;'> Invalid input! Please enter a number between 1 and 100.</p>";
            else if (userGuess < numberToGuess)
                resultMessage = "<p style='color: blue;'> Too low! Try again.</p>";
            else if (userGuess > numberToGuess)
                resultMessage = "<p style='color: blue;'> Too high! Try again.</p>";
            else
            {
                resultMessage = $"<p style='color: green;'> Congratulations! You guessed it right in {attempts} attempts.</p>";
                numberToGuess = new Random().Next(1, 101); // Reset the game
                attempts = 0;
            }
        }
    }

    // HTML structure
    string html = $@"
    <html>
    <head>
        <title>Guessing Game</title>
    </head>
    <body style='font-family: Arial, sans-serif; text-align: center;'>
        <h2>Welcome to the Web Guessing Game!</h2>
        <p><strong>Guess a number between 1 and 100.</strong></p>

        <form method='post'>
            <input type='number' name='userGuess' min='1' max='100' required>
            <button type='submit'>Guess</button>
        </form>

        {resultMessage} <!-- This ensures the result is displayed below the input field -->
    </body>
    </html>";

    context.Response.ContentType = "text/html"; // Ensure correct content type
    await context.Response.WriteAsync(html);
});

app.Run();

Step 4: Build and Run the Application

Before running the modified code, build the application using:

dotnet build

Then run the application:

dotnet run

After running, the application will be accessible at https://localhost:5001 (or as indicated in the console output).

---

3 Differences Between Console and Web Applications

Feature	Console Application	Web Application
UI	Command-line	Web-based
User Interaction	Text input/output	Browser-based interface
Use Case	Automation, testing, scripts	Web services, websites
Framework	.NET Console	ASP.NET Core

4 Explanation of Commands Used

Command	Description
dotnet new console -n MyConsoleApp	Creates a new console application project named MyConsoleApp.
dotnet new webapp -n MyWebApp	Creates a new web application project named MyWebApp.
cd MyConsoleApp / cd MyWebApp	Changes the directory to the specified project folder.
dotnet build	Compiles the project, checking for errors and generating necessary binaries.
dotnet run	Runs the application after it has been built.

This guide has provided a comprehensive, hands-on approach to building both C# console and web applications, highlighting their unique strengths and use cases.

Through the Guessing Game project, we explored how applications handle user interaction, logic processing, and UI design across different environments.

• Console applications are lightweight, efficient, and ideal for automation, scripting, and quick prototyping.
• Web applications offer a more interactive, browser-based experience, making them suitable for dynamic and scalable solutions.

By harnessing the robust capabilities of .NET, developers can create high-performance applications that cater to a wide range of business and technical needs. Whether building simple command-line tools or full-fledged web applications, mastering these concepts will provide a strong foundation for future development endeavors.

Keep learning, keep building!