Various String Class Methods in C#

Introduction to String Methods in C#

The string class in C# provides powerful methods for manipulating, comparing, formatting, and analyzing text data. These methods help developers efficiently perform tasks like **concatenation, searching, splitting, formatting, and modification**.

Concat() and Join() Methods

The Concat() method joins multiple strings, while Join() inserts a separator between elements of an array.

Example: Using Concat() and Join()

string firstName = "John";
string lastName = "Doe";
string fullName = string.Concat(firstName, " ", lastName);

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

string[] words = { "apple", "banana", "cherry" };
string joined = string.Join(", ", words);

Console.WriteLine(joined);  // Output: apple, banana, cherry
        

Equals() and Compare() Methods

The Equals() method checks for exact string equality, while Compare() compares two strings lexicographically.

Example: Using Equals() and Compare()

string str1 = "Hello";
string str2 = "hello";
bool isEqual = str1.Equals(str2, StringComparison.OrdinalIgnoreCase);

Console.WriteLine(isEqual);  // Output: True

int comparison = string.Compare(str1, str2, StringComparison.OrdinalIgnoreCase);
Console.WriteLine(comparison);  // Output: 0 (strings are equal)
        

Contains(), StartsWith(), EndsWith() Methods

These methods check whether a string **contains**, **starts with**, or **ends with** a specific substring.

Example: Searching in Strings

string text = "Welcome to C# programming";

bool containsCSharp = text.Contains("C#");
bool startsWithWelcome = text.StartsWith("Welcome");
bool endsWithProgramming = text.EndsWith("programming");

Console.WriteLine(containsCSharp);  // Output: True
Console.WriteLine(startsWithWelcome);  // Output: True
Console.WriteLine(endsWithProgramming);  // Output: True
        

Substring() and IndexOf() Methods

The Substring() method extracts a portion of a string, while IndexOf() returns the position of a substring.

Example: Extracting and Finding Strings

string message = "C# is powerful!";
int index = message.IndexOf("powerful");

Console.WriteLine(index);  // Output: 5

string subMessage = message.Substring(5, 8);
Console.WriteLine(subMessage);  // Output: powerful
        

Format(), PadLeft(), and PadRight() Methods

These methods allow formatting strings dynamically and aligning text.

Example: Formatting and Padding

string formatted = string.Format("Hello, {0}!", "John");
Console.WriteLine(formatted);  // Output: Hello, John!

string padded = "C#".PadRight(10, '-');
Console.WriteLine(padded);  // Output: C#--------
        

Replace(), ToUpper(), and ToLower() Methods

These methods allow modifying and converting text cases.

Example: Modifying Strings

string phrase = "I love Java";
string newPhrase = phrase.Replace("Java", "C#");

Console.WriteLine(newPhrase);  // Output: I love C#

Console.WriteLine(phrase.ToUpper());  // Output: I LOVE JAVA
Console.WriteLine(phrase.ToLower());  // Output: i love java
        

Key Points to Remember

• Concat() joins multiple strings, and Join() inserts separators.
• Equals() and Compare() are used for string comparison.
• Contains(), StartsWith(), and EndsWith() are useful for searching substrings.
• Substring() extracts text, while IndexOf() finds positions of substrings.
• Replace(), ToUpper(), and ToLower() modify string content.