String Handling In C# Complete Guide

1. Creating Strings

Strings can be created using string literals or the new keyword.

Example 1.1: Creating Strings

using System;

class Program
{
    static void Main()
    {
        // Using string literal
        string name1 = "Alice";

        // Using new keyword
        string name2 = new string('B', 5);

        Console.WriteLine("Name 1: " + name1);
        Console.WriteLine("Name 2: " + name2);
    }
}

Output:

Name 1: Alice
Name 2: BBBBB

2. String Length

The Length property returns the number of characters in a string.

Example 2.1: Finding the Length of a String

using System;

class Program
{
    static void Main()
    {
        string greeting = "Hello, World!";
        int length = greeting.Length;

        Console.WriteLine("The length of the string is: " + length);
    }
}

Output:

The length of the string is: 13

3. Accessing Characters

You can access individual characters in a string using the index operator.

Example 3.1: Accessing Characters

using System;

class Program
{
    static void Main()
    {
        string message = "Hello";

        // Accessing individual characters
        char firstLetter = message[0];
        char lastLetter = message[message.Length - 1];

        Console.WriteLine("First letter: " + firstLetter);
        Console.WriteLine("Last letter: " + lastLetter);
    }
}

Output:

First letter: H
Last letter: o

4. Modifying Strings

In C#, strings are immutable. However, you can create a new string by modifying the original string.

Example 4.1: Modifying Strings

using System;

class Program
{
    static void Main()
    {
        string original = "Hello";
        string modified = original.ToUpper() + " World!";

        Console.WriteLine("Original: " + original);
        Console.WriteLine("Modified: " + modified);
    }
}

Output:

Original: Hello
Modified: HELLO World!

5. String Concatenation

You can concatenate strings using the + operator or the Concat method.

Example 5.1: Concatenating Strings

using System;

class Program
{
    static void Main()
    {
        string str1 = "Hello";
        string str2 = "World";
        
        // Using + operator
        string result1 = str1 + ", " + str2 + "!";
        
        // Using Concat method
        string result2 = string.Concat(str1, ", ", str2, "!");
        
        Console.WriteLine("Result using + : " + result1);
        Console.WriteLine("Result using Concat: " + result2);
    }
}

Output:

Result using + : Hello, World!
Result using Concat: Hello, World!

6. String Comparison

You can compare strings using == operator or Equals() method.

Example 6.1: Comparing Strings

using System;

class Program
{
    static void Main()
    {
        string str1 = "Apple";
        string str2 = "apple";

        // Using == operator (case-sensitive)
        bool isEqual1 = str1 == str2;

        // Using Equals() method (case-sensitive)
        bool isEqual2 = str1.Equals(str2);

        // Using Equals() with StringComparison.OrdinalIgnoreCase
        bool isEqual3 = str1.Equals(str2, StringComparison.OrdinalIgnoreCase);

        Console.WriteLine("Using == : " + isEqual1);
        Console.WriteLine("Using Equals() : " + isEqual2);
        Console.WriteLine("Using Equals() with OrdinalIgnoreCase : " + isEqual3);
    }
}

Output:

Using == : False
Using Equals() : False
Using Equals() with OrdinalIgnoreCase : True

7. Searching in Strings

You can use methods like Contains, IndexOf, and LastIndexOf to search for substrings.

Example 7.1: Searching in Strings

using System;

class Program
{
    static void Main()
    {
        string sentence = "The quick brown fox jumps over the lazy dog";

        // Using Contains
        bool containsWord = sentence.Contains("fox");

        // Using IndexOf
        int indexFirstOccurrence = sentence.IndexOf("fox");

        // Using LastIndexOf
        int indexLastOccurrence = sentence.LastIndexOf("the");

        Console.WriteLine("Contains 'fox' : " + containsWord);
        Console.WriteLine("Index of first occurrence of 'fox' : " + indexFirstOccurrence);
        Console.WriteLine("Index of last occurrence of 'the' : " + indexLastOccurrence);
    }
}

Output:

Contains 'fox' : True
Index of first occurrence of 'fox' : 16
Index of last occurrence of 'the' : 40

8. Replacing Substrings

You can replace substrings using the Replace method.

Example 8.1: Replacing Substrings

using System;

class Program
{
    static void Main()
    {
        string sentence = "The quick brown fox jumps over the lazy dog";

        // Replacing 'fox' with 'cat'
        string modifiedSentence = sentence.Replace("fox", "cat");

        Console.WriteLine("Original: " + sentence);
        Console.WriteLine("Modified: " + modifiedSentence);
    }
}

Output:

Original: The quick brown fox jumps over the lazy dog
Modified: The quick brown cat jumps over the lazy dog

9. Splitting Strings

You can split a string into an array of substrings using the Split method.

Example 9.1: Splitting Strings

using System;

class Program
{
    static void Main()
    {
        string sentence = "The quick brown fox jumps over the lazy dog";

        // Splitting by spaces
        string[] words = sentence.Split(' ');

        Console.WriteLine("Words in the sentence:");
        foreach (string word in words)
        {
            Console.WriteLine(word);
        }
    }
}

Output: