C# String Class (original) (raw)

Last Updated : 13 Mar, 2025

In C#, a **string is a sequence of Unicode characters or an array of characters. The range of Unicode characters will be U+0000 to U+FFFF. The array of characters is also termed as the text. So the string is the representation of the text.

A string is represented by a class System.String. The String class is defined in the .NET base class library. In other words, a String object is a sequential collection of System.Char objects, which represent a string.

**Characteristics of String Class:

• The System.String class is immutable, i.e., once created, its state cannot be altered.
• Provides the properties like length used to get a total number of characters present in the given string.
• String objects can include a null character, which counts as part of the string’s length.
• It provides the position of the characters in the given string called as indexes.
• It allows empty strings. Empty strings are valid instances of String objects that contain zero characters.
• It also supports searching strings, comparison of strings, testing of equality, modifying the string, normalization of string, copying of strings, etc.
• It also provides several ways to create strings like using a constructor, using concatenation, etc.

**Example: Use of String class to print a message.

C# `

// C# Program to demonstrate the use of String class using System;

class Geeks { public static void Main() {
// Using String class String s = "Hello Geek";

    // Display the output
    System.Console.WriteLine(s);     
}

}

`

Constructor

**Example: Creating a string using String class constructor String(Char*, Int32) and String([]).

C# `

// C# program to create // string using the constructor String(Char*, Int32), and String(Chars[]); using System; class Geeks {

public static void Main() 
{ 
    char[] chars = { 'G', 'E', 'E', 'K', 'S' }; 

    // Create a string from a character array. 
    string s = new string(chars); 
    Console.WriteLine(s); 

    // Create a string that consists of 
    // a character repeated 5 times. 
    string s2 = new string('E', 5); 
    Console.WriteLine(s2); 
} 

}

`

Properties

In C# the String class has two properties.

• **Chars[Int32]: Gets the Char object at a specified position in the current String object.
• **Length: Gets the number of characters in the current String object.

**Example: Using the Properties of string class.

C# `

// C# program to demonstrate the // String Class Properties using System;

class Geeks { public static void Main() { string str = "GeeksforGeeks";

    // using Chars[Int32] & Length property 
    
    for (int i = 0; i <= str.Length - 1; i++) 
        Console.Write("{0} ", str[i]); 
} 

}

`

Output

G e e k s f o r G e e k s

Methods

**Example: Using Copy() and Compare() methods from the String class.

C# `

// C# program to illustrate // String class methods using System;

class Geeks { static void copymethod() { string s = "GeeksforGeeks"; string s2 = "geeks"; Console.WriteLine("Original Strings: str1 = " + "'{0}' and str2 ='{1}'", s, s2);

    Console.WriteLine("");

    Console.WriteLine("After Copy method");
    Console.WriteLine("");

    // using the Copy method
    // to copy the value of str1
    // into str2
    s2 = String.Copy(s);

    Console.WriteLine("Strings are str1 = " + "'{0}' and str2='{1}'", s, s2);
}

// Main method
static public void Main()
{
    // variables
    string s1 = "geeksforgeeks";
    string s2 = "geeksforgeeks";

    bool result;

    // Compare(string, string) method return true
    // because the given strings are equal
    result = String.Compare(s1, s2) == 0;

    Console.WriteLine("Result of Compare Method: " + result);

    // calling method
    copymethod();
}

}

`

Output

Result of Compare Method: True Original Strings: str1 = 'GeeksforGeeks' and str2 ='geeks'

After Copy method

Strings are str1 = 'GeeksforGeeks' and str2='GeeksforGeeks'

Operators

There are two operators string class

• **Equality(String, String): Determines whether two specified strings have the same value.
• **Inequality(String, String): Determines whether two specified strings have different values.

**Example: Using Equality and Inequality operators of string class.

C# `

// Using the Operators of string class using System;

class Geeks { public static void Main() { string s1 = "WelcomeToGeeks"; string s2 = "WelcomeToGeeks"; bool res;

    // Equality operator return true
    // as both string are equal
    res = s1 == s2;
    Console.WriteLine($"The strings \"{s1}\" and \"{s2}\" equal: {res}");

    // Inequality operator return false
    // as both string are equal
    res = s1 != s2;
    Console.WriteLine($"The strings \"{s1}\" and \"{s2}\" not equal: {res}");
}

}

`

Output

The strings "WelcomeToGeeks" and "WelcomeToGeeks" equal: True The strings "WelcomeToGeeks" and "WelcomeToGeeks" not equal: False

**Important Points:

• The maximum size of the String object in memory can be 2GB or about 1 billion characters.
• A string that has been declared but has not been assigned a value is null. Attempting to call methods on that string throws a NullReferenceException.
• String Class can not be inherited because it is a sealed class.
• String Class present in the System namespace.