Learn C# Programming

Master C# programming from basics to advanced concepts with our comprehensive tutorial series. Perfect for beginners and experienced developers.

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Tutorial Contents
Getting Started
Fundamentals
Control Flow
Functions
Arrays & Collections
Object-Oriented Programming
Advanced Topics

C# Input and Output

Input and output operations allow your program to interact with users and external data sources. C# provides various methods for reading input and displaying output.

Console Output

1. Console.WriteLine()

Displays text and moves to the next line:

Console.WriteLine("Hello, World!");
Console.WriteLine("This is on a new line");

// Output variables
int age = 25;
string name = "John";
Console.WriteLine("Name: " + name);
Console.WriteLine("Age: " + age);

2. Console.Write()

Displays text without moving to the next line:

Console.Write("Enter your name: ");
Console.Write("Hello ");
Console.Write("World");
// Output: Enter your name: Hello World

3. String Interpolation

Modern way to format output using $ prefix:

string name = "Alice";
int age = 30;
double salary = 50000.50;

Console.WriteLine($"Name: {name}");
Console.WriteLine($"Age: {age}");
Console.WriteLine($"Salary: {salary:C}");  // Currency format
Console.WriteLine($"Percentage: {0.85:P}"); // Percentage format
Console.WriteLine($"Date: {DateTime.Now:yyyy-MM-dd}");

4. String.Format()

Traditional string formatting method:

string name = "Bob";
int score = 95;

Console.WriteLine(String.Format("Student: {0}, Score: {1}", name, score));
Console.WriteLine("Student: {0}, Score: {1:F2}", name, score);

Console Input

1. Console.ReadLine()

Reads a complete line of text from the user:

Console.Write("Enter your name: ");
string name = Console.ReadLine();
Console.WriteLine($"Hello, {name}!");

2. Console.ReadKey()

Reads a single key press:

Console.WriteLine("Press any key to continue...");
ConsoleKeyInfo keyInfo = Console.ReadKey();
Console.WriteLine($"\nYou pressed: {keyInfo.Key}");

// Read key without displaying it
Console.WriteLine("Enter password: ");
ConsoleKeyInfo key = Console.ReadKey(true); // true = don't display

3. Converting Input

Converting string input to other data types:

// Converting to integer
Console.Write("Enter your age: ");
string ageInput = Console.ReadLine();
int age = int.Parse(ageInput);

// Safe conversion with TryParse
Console.Write("Enter a number: ");
string numberInput = Console.ReadLine();
if (int.TryParse(numberInput, out int number))
{
    Console.WriteLine($"You entered: {number}");
}
else
{
    Console.WriteLine("Invalid number format");
}

// Converting to double
Console.Write("Enter your height: ");
double height = double.Parse(Console.ReadLine());

// Converting to boolean
Console.Write("Are you a student? (true/false): ");
bool isStudent = bool.Parse(Console.ReadLine());

Formatting Output

1. Numeric Formatting

double value = 1234.5678;

Console.WriteLine($"{value:F2}");    // 1234.57 (2 decimal places)
Console.WriteLine($"{value:C}");     // $1,234.57 (currency)
Console.WriteLine($"{value:N}");     // 1,234.57 (number with commas)
Console.WriteLine($"{value:P}");     // 123,456.78% (percentage)
Console.WriteLine($"{value:E}");     // 1.234568E+003 (scientific)

int intValue = 42;
Console.WriteLine($"{intValue:D5}");  // 00042 (pad with zeros)
Console.WriteLine($"{intValue:X}");   // 2A (hexadecimal)

2. Date and Time Formatting

DateTime now = DateTime.Now;

Console.WriteLine($"{now:yyyy-MM-dd}");        // 2024-01-15
Console.WriteLine($"{now:HH:mm:ss}");          // 14:30:25
Console.WriteLine($"{now:dddd, MMMM dd, yyyy}"); // Monday, January 15, 2024
Console.WriteLine($"{now:hh:mm tt}");          // 02:30 PM

File Input/Output

1. Reading from Files

// Read entire file
string content = File.ReadAllText("data.txt");
Console.WriteLine(content);

// Read all lines
string[] lines = File.ReadAllLines("data.txt");
foreach (string line in lines)
{
    Console.WriteLine(line);
}

// Read line by line (memory efficient)
using (StreamReader reader = new StreamReader("data.txt"))
{
    string line;
    while ((line = reader.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
}

2. Writing to Files

// Write entire text
File.WriteAllText("output.txt", "Hello, World!");

// Write multiple lines
string[] lines = { "Line 1", "Line 2", "Line 3" };
File.WriteAllLines("output.txt", lines);

// Append to file
File.AppendAllText("output.txt", "\nAppended text");

// Write using StreamWriter
using (StreamWriter writer = new StreamWriter("output.txt"))
{
    writer.WriteLine("First line");
    writer.WriteLine("Second line");
}

Error Handling for I/O

try
{
    Console.Write("Enter a number: ");
    int number = int.Parse(Console.ReadLine());
    Console.WriteLine($"You entered: {number}");
}
catch (FormatException)
{
    Console.WriteLine("Error: Please enter a valid number");
}
catch (OverflowException)
{
    Console.WriteLine("Error: Number is too large");
}

// File I/O error handling
try
{
    string content = File.ReadAllText("nonexistent.txt");
}
catch (FileNotFoundException)
{
    Console.WriteLine("Error: File not found");
}
catch (UnauthorizedAccessException)
{
    Console.WriteLine("Error: Access denied");
}

💡 Best Practices

  • Always validate user input before processing
  • Use TryParse methods for safe type conversion
  • Use string interpolation ($"") for readable formatting
  • Handle exceptions when reading files or parsing input
  • Use using statements for file operations to ensure proper disposal
  • Provide clear prompts for user input

Frequently Asked Questions

C# is a modern, object-oriented programming language developed by Microsoft. It's part of the .NET framework and is used for developing various applications including web applications, desktop software, mobile apps, and games.

No! You can start learning C# immediately using our online compiler. For advanced development, you can install the .NET SDK and Visual Studio or VS Code on your computer.

Yes! C# has a clean syntax and strong type system that makes it beginner-friendly. Our tutorial starts from the basics and gradually progresses to advanced topics.

C# is versatile and can be used to build web applications (ASP.NET), desktop applications (WPF, WinForms), mobile apps (Xamarin), games (Unity), APIs, microservices, and much more.

The time varies based on your programming background. Complete beginners can learn the basics in 2-3 months with consistent practice. Our structured tutorial helps you progress systematically.

Master C# Programming with Our Comprehensive Tutorial

Our C# programming tutorial is designed to take you from a complete beginner to an advanced developer. Whether you're looking to build web applications, desktop software, or mobile apps, C# provides the foundation you need for modern software development.

Start with the basics like variables, data types, and control structures, then progress to advanced topics including object-oriented programming, LINQ, async programming, and more. Each lesson includes practical examples and exercises to reinforce your learning.

Join thousands of developers who have learned C# programming through our step-by-step tutorials. Begin your journey today and unlock the power of .NET development.