Strings in the C#

Strings in C#

In C#, strings are sequences of characters enclosed in double quotes (""). They are represented by the string keyword and are immutable, meaning their value cannot be changed after creation.

Creating Strings:

string greeting = "Hello, world!";

Accessing Characters:

You can access individual characters using index-based access:

char firstChar = greeting[0]; // 'H'

String Length:

To get the length of a string, use the Length property:

int length = greeting.Length; // 13

String Concatenation:

You can combine strings using the + operator or the Concat method:

string firstName = "Alice";

string lastName = "Johnson";

string fullName = firstName + " " + lastName; // "Alice Johnson"

string fullName2 = string.Concat(firstName, " ", lastName); // "Alice Johnson"

String Comparison:

You can compare strings using the == and != operators, or the Equals method:

string str1 = "Hello";

string str2 = "Hello";

if (str1 == str2)

{

    Console.WriteLine("The strings are equal.");

}

if (str1.Equals(str2))

{

    Console.WriteLine("The strings are equal.");

}

String Manipulation:

C# provides various methods for manipulating strings:

 * Substring: Extracts a portion of a string:

   string substring = greeting.Substring(7, 5); // "world"

 * IndexOf: Finds the index of a character or substring:

   int index = greeting.IndexOf('o'); // 4

 * LastIndexOf: Finds the last index of a character or substring:

   int lastIndex = greeting.LastIndexOf('o'); // 7

 * Replace: Replaces a substring with another:

   string newGreeting = greeting.Replace("world", "universe"); // "Hello, universe!"

 * ToLower: Converts a string to lowercase:

   string lowercaseGreeting = greeting.ToLower(); // "hello, world!"

 * ToUpper: Converts a string to uppercase:

   string uppercaseGreeting = greeting.ToUpper(); // "HELLO, WORLD!"

 * Trim: Removes leading and trailing whitespace:

   string trimmedString = "  Hello, world!  ".Trim(); // "Hello, world!"

String Formatting:

You can format strings using string interpolation or the String.Format method:

int age = 30;

string name = "John";

string formattedString = $"My name is {name} and I am {age} years old.";

string formattedString2 = String.Format("My name is {0} and I am {1} years old.", name, age);

StringBuilder:

For efficient string manipulation, especially when concatenating many strings, use the StringBuilder class:

StringBuilder builder = new StringBuilder();

builder.Append("Hello, ");

builder.Append("world!");

string finalString = builder.ToString();

By understanding these concepts, you can effectively work with strings in your C# applications.