C# Strings (original) (raw)

Last Updated : 04 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 an important concept, and sometimes people get confused about whether the string is a keyword, an object, or a class. So, let’s clear out this concept.

A string is represented by the class **System.String. The _“string” keyword is an alias for System.String class, and instead of writing System.String one can use _String, which is a shorthand for **System.String class. So we can say that both string and String can be used as an alias of System.String class. So string is an _object of System.String class.

**Example:

_// creating the string using string keyword
_string s1 = “GeeksforGeeks”;

_// creating the string using String class
_String s2 = “GFG”;

_// creating the string using String class
_System.String s3 = “Pro Geek”;

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. The maximum size of String object in memory is 2GB or about 1 billion characters. **System.String class is immutable, i.e, once created, its state cannot be altered.

C# `

// C# program to declare string using // string, String and System.String // and initialization of string using System;

class Geeks { // Main Method static void Main(string[] args) { // declare a string Name using // "System.String" class System.String Name;

    // initialization of String
    Name = "Geek";

    // declare a string id using 
    // using an alias(shorthand) 
    // "String" of System.String
    // class
    String id;
    
    // initialization of String
    id = "33";

    // declare a string mrk using 
    // string keyword
    string mrk;
    
    // initialization of String
    mrk = "97";
    
    // Declaration and initialization of
    // the string in a single line
    string rank = "1";

    // Displaying Result
    Console.WriteLine("Name: {0}", Name);
    Console.WriteLine("Id: {0}", id);
    Console.WriteLine("Marks: {0}", mrk);
    Console.WriteLine("Rank: {0}", rank);
}

}

`

Output

Name: Geek Id: 33 Marks: 97 Rank: 1

Key Characteristics of Strings

• **Immutable: Once created, the content of a string cannot be altered. Any modification results in the creation of a new string.
• **Reference Type: Strings are reference types, but they behave like value types in some scenarios, such as comparison.
• **Unicode Support: Strings can contain any Unicode character, allowing support for multiple languages.
• **Null and Embedded Nulls: Strings can be null and may also contain embedded null characters (\0).
• **Operator Overloading: Strings support operator overloading, such as + for concatenation and == for comparison.

**String Class Properties: The String class has two properties as follows:

• **Chars: It is used to get the Char object at a specified position in the current String object.
• **Length: It is used to get the number of characters in the current String object. To know more about the string class properties please go to String Properties in C#.

**Reading String from User-Input

A string can be read out from the user input. ReadLine() method of console class is used to read a string from user input.

**Example:

C# `

// C# program to demonstrate Reading // String from User-Input using System;

class Geeks {
// Main Method static void Main(string[] args) {

    Console.WriteLine("Enter the String");

    // Declaring a string object read_user 
    // and taking the user input using 
    // ReadLine() method
    String read_user = Console.ReadLine();

    // Displaying the user input
    Console.WriteLine("User Entered: " + read_user);

}

}

`

Input:

Hello Geeks !

Output:

User Entered: Hello Geeks !

Different Ways to Create Strings

**Example:

C# `

// Different Methods for Creating // String in C# using System;

public class GFG { // Main Method static public void Main () {

      // Creating String using string literal
    String str = "Geeks";
      Console.WriteLine("Method 1: " + str);
  
      // Creating String using concatenation
      String str2 = str + "ofGeeks";
      Console.WriteLine("Method 2: " + str2);
      
      // Creating a string using a constructor
      char[] chars = { 'G', 'E', 'E', 'K', 'S' };
    string str3 = new string(chars);
      Console.WriteLine("Method 3: " + str3);
      
      // Creating a string using a property or a method
      String s = "Geeks For Geeks";
      
      // Index of 
    int start = s.IndexOf(" ") + 1;
      int end = s.IndexOf(" ", start) - start;
      string str4 = s.Substring(start, end);
      Console.WriteLine("Method 4: " + str4);
  
      // Creating a string using formatting
      int i=1;
      int j=2;
      int sum= i + j;
      String str5 = string.Format("Addition of {0} with {1} is {2}"
                                , i , j , sum );
      Console.WriteLine("Method 5: " + str5);
      
}

}

`

Output

Method 1: Geeks Method 2: GeeksofGeeks Method 3: GEEKS Method 4: For Method 5: Addition of 1 with 2 is 3

C# String Operations

There are multiple String Operations which we can perform in String in C#. Let us demonstrate the operations using the example as mentioned below:

**Example 1: For performing string operation of interpolation

C# `

using System;

public class GFG { // Main Method static public void Main () { string name = "GeeksforGeeks";

    // Interpolation is performed
    string res = $"{name} is the Organisation Name.";
    
    // Printing the String
    Console.WriteLine(res);
    Console.WriteLine("Length: " + res.Length);
}

}

`

Output

GeeksforGeeks is the Organisation Name. Length: 39

**Example 2: for performing trim, replace and concatenate operation

C# `

using System;

public class GFG { static public void Main () { string first = " GeEks "; string second = " forGeeks ";

    // trim the String
    first=first.Trim();
    second=second.Trim();
    
    // Checking element at index 2 first
    Console.WriteLine("Element at index 2: " + first[2]);
    
    // replacing the element in String
    first=first.Replace("E","e");
    Console.WriteLine(first+second);
}

}

`

Output

Element at index 2: E GeeksforGeeks

In the above, two example we have explored many methods we are not full aware of so, there is a list of Methods associated with Strings in C# attached below.

Methods of C# String

String Arrays

We can also create the array of string and assigns values to it. The string arrays can be created as follows:

String [] array_variable = new String[Length_of_array]

**Example:

C# `

// C# program for an array of strings using System;

class Geeks {
// Main Method static void Main(string[] args) { String[] str_arr = new String[3];

    // Initialising the array of strings
    str_arr[0] = "Geeks";
    str_arr[1] = "For";
    str_arr[2] = "Geeks";

    // printing String array
    for(int i = 0; i < 3; i++) {
        Console.WriteLine("value at Index position " + i
                          + " is " + str_arr[i]);
    }

}

}

`

Output

value at Index position 0 is Geeks value at Index position 1 is For value at Index position 2 is Geeks

**String vs System.String

**Note: In .NET, the text is stored as a sequential collection of the Char objects so there is no null-terminating character at the end of a C# string. Therefore a C# string can contain any number of embedded null characters (‘\0’).