C# Strings

Welcome to The Coding College! In this tutorial, we’ll dive deep into C# Strings, an essential concept for handling and manipulating text data in C#. Strings are widely used in programming, and mastering them will greatly enhance your coding skills.

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What is a String in C#?

A string in C# is a sequence of characters enclosed within double quotes (" "). Strings are immutable, meaning once created, they cannot be changed. However, C# provides many methods to manipulate strings efficiently.

In C#, strings belong to the System.String class, and you can perform various operations like concatenation, comparison, splitting, and more.

Declaring Strings in C#

Here’s how you can declare and initialize strings in C#:

using System;

class Program
{
    static void Main()
    {
        string greeting = "Hello, World!";
        Console.WriteLine(greeting);
    }
}

// Output:
// Hello, World!

String Concatenation

String concatenation combines two or more strings into one.

Using the + Operator

string firstName = "John";
string lastName = "Doe";
string fullName = firstName + " " + lastName;

Console.WriteLine(fullName);  // Output: John Doe

Using String.Concat() Method

string fullName = String.Concat("John", " ", "Doe");
Console.WriteLine(fullName);  // Output: John Doe

Using String Interpolation (Recommended)

String interpolation is a modern and cleaner way to concatenate strings using $.

string firstName = "John";
string lastName = "Doe";

string fullName = $"My name is {firstName} {lastName}.";
Console.WriteLine(fullName);  // Output: My name is John Doe.

Common String Methods in C#

The String class in C# provides several built-in methods for manipulating strings:

String Examples

1. String Length and Case Conversion

using System;

class StringExample
{
    static void Main()
    {
        string text = "Hello, C#";

        Console.WriteLine("Length of string: " + text.Length);
        Console.WriteLine("Uppercase: " + text.ToUpper());
        Console.WriteLine("Lowercase: " + text.ToLower());
    }
}

// Output:
// Length of string: 9
// Uppercase: HELLO, C#
// Lowercase: hello, c#

2. Substring and Replace

using System;

class StringExample
{
    static void Main()
    {
        string text = "Welcome to C# Programming";

        Console.WriteLine("Substring: " + text.Substring(11, 2));  // Output: C#
        Console.WriteLine("Replace: " + text.Replace("C#", "Java"));  // Output: Welcome to Java Programming
    }
}

3. Checking Substrings and Splitting Strings

using System;

class StringExample
{
    static void Main()
    {
        string text = "Apple, Banana, Cherry";

        // Check if text contains "Banana"
        Console.WriteLine("Contains Banana: " + text.Contains("Banana"));

        // Split the string
        string[] fruits = text.Split(',');
        foreach (string fruit in fruits)
        {
            Console.WriteLine(fruit.Trim());
        }
    }
}

// Output:
// Contains Banana: True
// Apple
// Banana
// Cherry

String Immutability in C#

Strings in C# are immutable, meaning once you create a string, you cannot change its content. Instead, operations like concatenation or replacement create new string objects.

Example:

string str = "Hello";
str = str + " World";

Console.WriteLine(str);  // Output: Hello World

Here, the original str is not modified; a new string is created.

Use StringBuilder for Efficiency

If you perform many string operations (like concatenations in a loop), use the StringBuilder class for better performance.

using System.Text;

class Program
{
    static void Main()
    {
        StringBuilder sb = new StringBuilder();

        for (int i = 1; i <= 5; i++)
        {
            sb.Append("Number: " + i + "\n");
        }

        Console.WriteLine(sb.ToString());
    }
}

// Output:
// Number: 1
// Number: 2
// Number: 3
// Number: 4
// Number: 5

Benefits of C# Strings

1. Simple to Use: Intuitive and beginner-friendly.
2. Versatile: Offers powerful methods for manipulation.
3. Efficient: Use StringBuilder for large string operations.
4. Standardized: Works seamlessly with .NET libraries and tools.

Conclusion

Strings are an essential part of C# programming, and understanding their methods and behavior will help you write cleaner and more efficient code. Use string methods wisely and leverage StringBuilder for optimal performance in complex operations.

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