String Class

The System.String class is fundamental to text manipulation in .NET. It provides a rich set of methods for creating, comparing, searching, and modifying strings. Because strings are immutable, any operation that appears to modify a string actually creates a new string instance.

• public String(char* value)
  Initializes a new instance of the String class to the specified pointer to a character array.
• public String(char* value, int startIndex, int length)
  Initializes a new instance of the String class to the specified pointer to a character array, a starting index, and a length.
• public String(char[] value)
  Initializes a new instance of the String class to the value indicated by a specified array of 16-bit unsigned integer code units.
• public String(char[] value, int startIndex, int length)
  Initializes a new instance of the String class to the value indicated by a specified array of 16-bit unsigned integer code units, a starting index, and a count.
• public String(char[] value, int startIndex, int length, IFormatProvider provider)
  Initializes a new instance of the String class to the value indicated by a specified array of 16-bit unsigned integer code units, a starting index, a count, and culture-specific formatting information.

• public static String Empty
  Represents an empty string. This field is read-only.
• public int Length { get; }
  Gets the number of characters in the current String object.
• public char Chars(int index) { get; }
  Gets the specified character at position 'index' in the current String object.

• public static int Compare(string strA, string strB)
  Compares two strings.
• public static int Compare(string strA, string strB, bool ignoreCase)
  Compares two strings, ignoring or considering case.
• public static int CompareTo(string other)
  Compares the current string with another string.
• public static string Concat(string str0, string str1)
  Concatenates the specified instances of String.
• public static string Format(string format, object arg0)
  Formats a string by using the specified format string and arguments.
• public bool Contains(string value)
  Determines whether the string contains a specified substring.
• public int IndexOf(char value)
  Returns the zero-based index of the first occurrence of the specified Unicode character within this instance.
• public int IndexOf(string value)
  Returns the zero-based index of the first occurrence of a specified substring within this instance.
• public string ToLower()
  Converts this instance to lowercase.
• public string ToUpper()
  Converts this instance to uppercase.
• public string Trim()
  Removes all leading and trailing white space characters from the current String object.
• public char[] ToCharArray()
  Copies the characters in this instance to a Unicode character array.

• public static bool operator == (string left, string right)
  Compares two strings for equality.
• public static bool operator != (string left, string right)
  Compares two strings for inequality.
• public static string operator + (string left, string right)
  Concatenates two strings.

using System;

public class StringExample
{
    public static void Main(string[] args)
    {
        string greeting = "Hello, World!";
        Console.WriteLine(greeting); // Output: Hello, World!

        string name = "Alice";
        string message = string.Concat("Welcome, ", name, "!");
        Console.WriteLine(message); // Output: Welcome, Alice!

        string sentence = "The quick brown fox jumps over the lazy dog.";
        bool containsFox = sentence.Contains("fox");
        Console.WriteLine($"Does the sentence contain 'fox'? {containsFox}"); // Output: Does the sentence contain 'fox'? True

        int index = sentence.IndexOf("jumps");
        Console.WriteLine($"The word 'jumps' starts at index: {index}"); // Output: The word 'jumps' starts at index: 20

        string upperCase = greeting.ToUpper();
        Console.WriteLine($"Uppercase version: {upperCase}"); // Output: Uppercase version: HELLO, WORLD!

        string trimmed = "   Trim me!   ";
        Console.WriteLine($"Trimmed: '{trimmed.Trim()}'"); // Output: Trimmed: 'Trim me!'
    }
}