C# Output

Output Methods

Console.WriteLine("Line 1");
Console.WriteLine("Line 2");

Console.Write("Same ");
Console.Write("Line");

Console.WriteLine(42);
Console.WriteLine(3.14);

int age = 25;
Console.WriteLine(age);

🔹 Console.WriteLine()

The Console.WriteLine() method in C# outputs text to the console and automatically appends a newline character at the end. This means each call to WriteLine() moves the cursor to the beginning of the next line, making it perfect for displaying separate lines of output clearly. For example, Console.WriteLine("First line"); Console.WriteLine("Second line"); will print two distinct lines. It’s commonly used for messages, debugging logs, and formatted data displays where line separation improves readability. You can pass strings, numbers, variables, or expressions directly into the method for versatile output.

using System;

class WriteLineExample
{
    static void Main()
    {
        Console.WriteLine("First line");
        Console.WriteLine("Second line");
        Console.WriteLine("Third line");
        
        // Print numbers
        Console.WriteLine(100);
        Console.WriteLine(3.14159);
    }
}

🔹 Console.Write()

The Console.Write() method prints text to the console without moving to a new line after execution. Unlike WriteLine(), it keeps the cursor on the same line, allowing subsequent output to continue directly after the previous text. This is particularly useful for creating formatted outputs, progress indicators, or prompts where content needs to stay inline. For instance, Console.Write("Hello "); Console.Write("World!"); produces "Hello World!" on a single line. It supports all data types and string concatenation, making it essential for building dynamic, single-line console interfaces.

using System;

class WriteExample
{
    static void Main()
    {
        Console.Write("Hello ");
        Console.Write("World");
        Console.Write("!");
        
        Console.WriteLine();  // Move to new line
        
        Console.Write("A");
        Console.Write("B");
        Console.Write("C");
    }
}

🔹 Printing Variables

Printing variables in C# involves outputting their stored values directly to the console using WriteLine() or Write(). You can print variables alone or combine them with descriptive text using concatenation (+ operator) for clearer context. For example, int age = 25; Console.WriteLine("Age: " + age); displays "Age: 25". This works with all data types—strings, integers, booleans, and decimals—making it invaluable for debugging and user feedback. Properly formatted variable output enhances program transparency and helps users understand the data being processed.

using System;

class Variables
{
    static void Main()
    {
        string name = "Alice";
        int age = 25;
        double height = 5.6;
        bool isStudent = true;
        
        // Print variables directly
        Console.WriteLine(name);
        Console.WriteLine(age);
        
        // Combine text and variables
        Console.WriteLine("Name: " + name);
        Console.WriteLine("Age: " + age);
        Console.WriteLine("Height: " + height + " feet");
        Console.WriteLine("Student: " + isStudent);
    }
}

🔹 String Concatenation

String concatenation remains a foundational technique in C# for joining multiple string values into one cohesive output. Using the + operator, developers can combine literals, variables, and expressions, such as "Hello, " + userName + "!". While intuitive, excessive concatenation in loops can impact performance due to string immutability. For repeated operations, StringBuilder is more efficient. Understanding when to use concatenation versus interpolation or StringBuilder is key for writing optimized, maintainable code that produces clear, user-friendly text outputs in applications ranging from console programs to web interfaces.

using System;

class Concatenation
{
    static void Main()
    {
        string firstName = "John";
        string lastName = "Doe";
        int age = 30;
        
        // Concatenate strings
        Console.WriteLine(firstName + " " + lastName);
        
        // Concatenate strings and numbers
        Console.WriteLine("Name: " + firstName + " " + lastName);
        Console.WriteLine(firstName + " is " + age + " years old");
        
        // Multiple concatenations
        string fullInfo = "User: " + firstName + ", Age: " + age;
        Console.WriteLine(fullInfo);
    }
}

🔹 String Interpolation

String interpolation in C# offers a streamlined syntax for embedding variables and expressions within strings by prefixing with $ and wrapping them in {}. It eliminates the clutter of concatenation operators and improves code clarity. For instance, $"The result is {value * 2}" directly incorporates calculations. Interpolation also supports formatting specifiers, such as {price:C2} for currency. This method is not only more readable but also reduces runtime errors from incorrect string assembly, making it a best practice for generating dynamic text in modern C# development.

using System;

class Interpolation
{
    static void Main()
    {
        string name = "Sarah";
        int age = 28;
        double salary = 50000.50;
        
        // String interpolation (easier to read)
        Console.WriteLine($"Name: {name}");
        Console.WriteLine($"Age: {age}");
        Console.WriteLine($"{name} is {age} years old");
        Console.WriteLine($"Salary: ${salary}");
        
        // Can include expressions
        Console.WriteLine($"Next year: {age + 1}");
        Console.WriteLine($"Monthly: ${salary / 12}");
    }
}

🔹 Formatting Numbers

Formatting numbers in C# controls how numeric values appear when converted to strings, using standard or custom format specifiers. This includes setting decimal places, currency symbols, percentage signs, and digit grouping. For example, price.ToString("C2") formats as currency with two decimals, like "$19.99". Common specifiers include "N" for number formatting, "P" for percentages, and "F" for fixed-point. Proper number formatting improves data presentation in reports, user interfaces, and financial applications, ensuring clarity, localization, and professional appearance in output.

using System;

class Formatting
{
    static void Main()
    {
        double price = 19.99;
        double percent = 0.85;
        int number = 1234567;
        
        // Currency format
        Console.WriteLine($"Price: {price:C}");
        
        // Fixed decimal places
        Console.WriteLine($"Value: {price:F2}");
        
        // Percentage
        Console.WriteLine($"Score: {percent:P}");
        
        // Number with commas
        Console.WriteLine($"Population: {number:N0}");
    }
}

🔹 Escape Sequences

Escape sequences create special characters in strings. Use backslash (\) followed by a character to create tabs, new lines, and quotes.

using System;

class EscapeSequences
{
    static void Main()
    {
        // New line
        Console.WriteLine("Line 1\nLine 2");
        
        // Tab
        Console.WriteLine("Name:\tJohn");
        Console.WriteLine("Age:\t25");
        
        // Quotes
        Console.WriteLine("She said \"Hello\"");
        
        // Backslash
        Console.WriteLine("Path: C:\\Users\\Documents");
    }
}