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Strings in C#

Updated on Sep 3, 2025
 
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Table of Content

Strings are an array of characters. They are stored as a sequential read only collection of char objects in the system internally. Strings in C# don't contain null characters in the end.

There are various methods to declare and initialize strings. Some of these are given as follows:

1. The string is only declared and not initialized. This is given below:

string str;

2. The string is declared and initialized to NULL. This is given below:

string str = NULL:

3. The string is declared and initialized to a sequence of characters. This is given below:

string str = “C# is fun”;

4. The String constructor can be used when a string is created from char*, char[ ] or sbyte*. This is given below:

char[ ] alphabets = { ‘s’, ‘t’, ‘r’, ‘i’, ‘n’, ‘g’};
string str = new string(alphabets);

String Constructors

The different constructors and their description is given as follows:

Constructors

Description

String (Char*)

This constructor initializes a new instance of the String class to the value indicated by a specified pointer to an array of Unicode characters.

String(Char[])

This constructor initializes a new instance of the String class to the value indicated by an array of Unicode characters.

String(SByte*)

This constructor initializes a new instance of the String class to the value indicated by a pointer to an array of 8-bit signed integers.

String(Char, Int32)

This constructor initializes a new instance of the String class to the value indicated by a specified Unicode character repeated a specified number of times.

String(Char*, Int32, Int32)

This constructor initializes a new instance of the String class to the value indicated by a specified pointer to an array of Unicode characters, a starting character position within that array, and a length.

String(Char[], Int32, Int32)

This constructor initializes a new instance of the String class to the value indicated by an array of Unicode characters, a starting character position within that array, and a length

String(SByte*, Int32, Int32)

This constructor initializes a new instance of the String class to the value indicated by a specified pointer to an array of 8-bit signed integers, a starting position within that array, and a length.

String(SByte*, Int32, Int32, Encoding)

This constructor initializes a new instance of the String class to the value indicated by a specified pointer to an array of 8-bit signed integers, a starting position within that array, a length, and an Encoding object.

Table: Constructors in String in C#
Source: MSDN

String Properties

The different properties and their description is given as follows:

Properties

Description

Chars [Int32]

This property gets the Char object at a specified position in the current String object.

Length

This property gets the number of characters in the current String object.

Table: Properties in String in C#
Source: MSDN

String Methods

The different methods and their description is given as follows:

Methods

Description

Clone()

This method returns a reference to the given instance of String.

Compare()

This method compares two specified String objects and returns an integer that indicates their relative position in the sort order.

CompareTo()

This method compares this instance with a specified object or String and returns an integer that indicates whether this instance precedes, follows, or appears in the same position in the sort order as the specified object or String.

Concat()

This method concatenates one or more instances of String, or the String representations of the values of one or more instances of Object.

Copy()

This method creates a new instance of String with the same value as the specified String.

Equals()

This method determines whether two String objects have the same value.

Format()

This method converts the value of objects to strings based on the formats specified and inserts them into another string.

Insert()

This method returns a new string in which a specified string is inserted at a specified index position in this instance.

Join()

This method concatenates the elements of a specified array or the members of a collection, using the specified separator between each element or member.

PadLeft()

This method returns a new string of a specified length in which the beginning of the current string is padded with spaces or with a specified Unicode character.

PadRight()

This method returns a new string of a specified length in which the end of the current string is padded with spaces or with a specified Unicode character.

Remove()

This method returns a new string in which a specified number of characters from the current string are deleted.

Replace()

This method returns a new string in which all occurrences of a specified Unicode character or String in the current string are replaced with another specified Unicode character or String.

Split()

This method returns a string array that contains the substrings in this instance that are delimited by elements of a specified string or Unicode character array.

ToLower()

This method returns a copy of the string converted to lowercase.

ToString()

This method converts the value of this instance to a String.

ToUpper()

This method returns a copy of this string converted to uppercase.

Trim()

This method returns a new string in which all leading and trailing occurrences of a set of specified characters from the current String object are removed.

Table: Methods in String in C#
Source: MSDN

String Operations

Some of the programs related to strings are given below:

Finding length of a string

The program to find the length of a string is given as follows:

using System;
namespace StringDemo
{
  class Example
  {
     static void Main(string[] args)
     {
       string str = "Laptops and Mobiles";
       Console.WriteLine("The Length of the string \"{0}\" is : {1} ",str, str.Length);
     }
  }
}

Source Code: Program to find length of string in C#

The output of the above program is as follows:

The Length of the string "Laptops and Mobiles" is : 19
Comparing Two Strings

A program to compare two strings and find if they are equal or not is given as follows:

using System;
namespace StringDemo
{
  class Example
  {
     static void Main(string[] args)
     {
        string s1 = "Apple";
        string s2 = "Apple";
        if (String.Compare(s1, s2) == 0)
        {
           Console.WriteLine("The strings are equal");
        }
        else
        {
           Console.WriteLine("The strings are not equal");
        }
     }
  }
}

Source Code: Program to compare two strings in C#

The output of the above program is as follows:

The strings are equal

Obtain last 4 characters from string in C#

A program that obtains the last 4 characters from a string is given as follows:

using System;
public class Demo
{
public static void Main()
{
    string str = "Strings in C#";
    string resultStr = str.Substring(str.Length - 4);
    Console.WriteLine("Original string: {0}", str);
    Console.WriteLine("Resultant string: {0}", resultStr);
}
}

Source Code: Program to obtain the last 4 characters from a string in C#

The output of the above program is as follows:

Original string: Strings in C#
Resultant string: n C#

Obtain last 2 characters from string using Regex in C#

A program that obtains the last 2 characters from a string using Regex is given as follows:

using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
  string str = "Strings in C#";
  Console.WriteLine("Original string: {0}", str);
  Console.Write("Resultant string: ");
  Console.WriteLine(Regex.Match(str,@"(.{2})\s*$"));
}
}

Source Code: Program to obtain the last 2 characters from a string using Regex in C#

The output of the above program is as follows:

Original string: Strings in C#
Resultant string: C#

Print first letter of each word in a string using Regex in C#

A program that prints the first letter of each word in a string using Regex is given as follows:

using System;
using System.Text.RegularExpressions;
namespace RegexDemo
{
  public class Example
  {
     private static void showMatch(string str, string exp)
     {
        Console.WriteLine("The string: " + str);
        Console.WriteLine("The Expression: " + exp);
        MatchCollection matchCol = Regex.Matches(str, exp);
        foreach (Match m in matchCol)
        {
           Console.WriteLine(m);
        }
     }
     public static void Main(string[] args)
     {
        string str = "Strings in C#";
        Console.WriteLine("Display first letter of each word!");
        showMatch(str, @"\b[a-zA-Z]");
     }
  }
}

Source Code: Program to print the first letter of each word in a string using Regex in C#

The output of the above program is as follows:

Display first letter of each word!
The string: Strings in C#
The Expression: \b[a-zA-Z]
S
i
C

Print first letter of each word in a string in C#

A program that prints the first letter of each word in a string is given as follows:

using System;
public class Example {
public static void Main() {
 string str = "Strings in C#";
 Console.WriteLine("String is: " + str);
 Console.WriteLine("Displaying first letter of each word");
 string[] splitString = str.Split();
 foreach(string i in splitString) {
  Console.WriteLine(i.Substring(0, 1));
 }
}
}

Source Code: Program to print the first letter of each word in a string in C#

The output of the above program is as follows:

String is: Strings in C#
Displaying first letter of each word
S
i
C

Find the index of a word in a string in C#

A program that finds the index of a word in a string is given as follows:

using System;
public class Demo
{
   public static void Main()
   {
       string[] str = new string[]
       {
           "Mango",
           "Apple",
           "Guava",
           "Orange",
           "Peach"
       };
Console.WriteLine("The given array is:");
for (int i = 0; i < str.Length; i++)
       {
           Console.WriteLine(str[i]);
       }
int index = Array.IndexOf(str, "Peach");
Console.Write("The element Peach is found the index: ");
       Console.WriteLine(index);
   }
}

Source Code: Program to find the index of a word in a string in C#

The output of the above program is as follows:

The given array is:
Mango
Apple
Guava
Orange
Peach
The element Peach is found the index: 4

List all Substrings in a given String using C#

A program that lists all the substrings in a string is given as follows:

using System;
public class Demo
{
  public static void Main()
  {
     string str = "boat";
     Console.WriteLine("The substrings for boat are:");
     for (int i = 1; i < str.Length; i++)
     {
        for (int j = 0; j <= str.Length - i; j++)
        {
           string substring = str.Substring(j, i);
           Console.WriteLine(substring);
        }
     }
  }
}

Source Code: Program to list all the substrings in a string in C#

The output of the above program is as follows:

The substrings for boat are:
b
o
a
t
bo
oa
at
boa
oat

Split a string on spaces in C#

A program that splits a string on spaces is given as follows:

using System;
using System.Linq;
using System.IO;
class Example
{
   static void Main()
   {
       string str = "Strings in C#";
       Console.WriteLine("The original string is: " + str);
       string[] strSplit = str.Split(' ');
       Console.WriteLine("The splitted string is:");
       foreach (string s in strSplit)
       {
           Console.WriteLine(s);
       }
   }
}

Source Code: Program to split a string on spaces in C#

The output of the above program is as follows:

The original string is: Strings in C#
The splitted string is:
Strings
in
C#

Match all the digits in a string in C#

A program that matches all the digits in a string is given as follows:

using System;
using System.Text.RegularExpressions;
namespace Demo
{
  class Example
  {
     private static void showMatch(string str, string exp)
     {
        Console.WriteLine("The Expression: " + exp);
        MatchCollection matchCol = Regex.Matches(str, exp);
        Console.WriteLine("The digits are:");
        foreach (Match m in matchCol)
        {
           Console.WriteLine(m);
        }
     }
     static void Main(string[] args)
     {
        string str = "5 and 7 are prime numbers";
        Console.WriteLine("Getting digits from a string");
        Console.WriteLine("The string is: " + str);
        showMatch(str, @"\d+");
     }
  }
}

The output of the above program is as follows:

Getting digits from a string
The string is: 5 and 7 are prime numbers
The Expression: \d+
The digits are:
5
7

Remove the end part of a string in C#

A program that removes the end part of a string is given as follows:

using System;
using System.Text.RegularExpressions;
namespace Example
{
  class Example
  {
     static void Main(string[] args)
     {
       string str1 = "I love apples!";
       string str2 = System.Text.RegularExpressions.Regex.Replace(str1, "!", ".");
       Console.WriteLine("str1: {0}", str1);
       Console.WriteLine("str2: {0}", str2);
     }
  }
}

Source Code: Program to remove the end part of a string in C#

The output of the above program is as follows:

str1: I love apples!
str2: I love apples.

Replace parts of a string with Regex in C#

A program that replaces parts of a string using Regex is given as follows:

using System;
using System.Text.RegularExpressions;
namespace Demo
{
  class Example
  {
     static void Main(string[] args)
     {
        string str1 = "Apples are red";
        Console.WriteLine("Initial string: " + str1);
       string str2 = Regex.Replace(str1, "r.d", "green");
       Console.WriteLine("Modified string: " + str2);
     }
  }
}

Source Code: Program to replace parts of a string using Regex in C#

The output of the above program is as follows:

Initial string: Apples are red
Modified string: Apples are green

Remove duplicate characters from String in C#

A program that removes duplicate characters from a string is given as follows:

using System;
using System.Linq;
using System.Collections.Generic;
namespace Demo
{
  class Example
  {
     static void Main(string[] args)
     {
       string str = "ssskkyyy";
       Console.WriteLine("Initial String: " + str);
       var newStr = new HashSet<char>(str);
       Console.Write("String after removing duplicates: ");
       foreach (char c in newStr)
          Console.Write(c);   
     }
  }
}

Source Code: Program to remove duplicate characters from a string in C#

The output of the above program is as follows:

Initial String: ssskkyyy
String after removing duplicates: sky

Removing white spaces using String.Empty in C#

A program that removes white spaces from a string is given as follows:

using System;
using System.Text;
class Demo
{
   static void Main()
   {
       StringBuilder str = new StringBuilder("Edward Mason");
       Console.WriteLine("Initial string: " + str.ToString());
       str.Replace(" ", String.Empty);
       Console.WriteLine("String after removing white spaces: " + str.ToString());
   }
}

Source Code: Program to remove white spaces from a string in C#

The output of the above program is as follows:

Initial string: Edward Mason
String after removing white spaces: EdwardMason
using System;  
public class Demo
{  
   public static void Main()
 {
   string str;
   int c = 0, count = 1;
   str = "I love mangoes";
   while (c <= str.Length - 1)
   {
       if(str[c]==' ' || str[c]=='\n' || str[c]=='\t')
       {
           count++;
       }
       c++;
   }
   Console.WriteLine("String: {0}", str);
   Console.WriteLine("Total words: {0}", count);
 }
}

The output of the above program is as follows:

String: I love mangoes
Total words: 3

Get first three letters from every string in C#

A program that gets the first three letters from all strings is given as follows:

using System;
using System.Linq;
using System.Collections.Generic;
class Example
{
   static void Main()
   {
       List<object> list = new List<object> { "John", "Mary", "Peter", "Susan", "Lucy" };
       IEnumerable<string> result =  list.AsQueryable()
           .Cast<string>()
           .Select(str => str.Substring(0, 3));
       Console.WriteLine("First 3 letters from all strings are:");
       foreach (string s in result)
         Console.WriteLine(s);
       }
}

Source Code: Program that gets the first three letters from all strings in C#

The output of the above program is as follows:

First 3 letters from all strings are:
Joh
Mar
Pet
Sus
Luc

Split a string into elements of a string array in C#

A program that splits a string into elements of a string is given as follows:

using System;
class Example
{
   static void Main()
   {
       string str = "The ocean is blue";
       string[] elementStr = str.Split(' ');
       Console.WriteLine("String: " + str);
       Console.WriteLine("Separate elements of string:");
       foreach (string word in elementStr)
       {
           Console.WriteLine(word);
       }
   }
}

Source Code: Program that splits a string into elements of a string in C#

The output of the above program is as follows:

String: The ocean is blue
Separate elements of string:
The
ocean
is
blue

Split a string using regular expressions in C#

A program that splits a string using regular expressions is given as follows:

using System;
using System.Text.RegularExpressions;
class Demo
{
   static void Main()
   {
       string str = "The ocean is blue";
       string[] result = Regex.Split(str, " ");
       Console.WriteLine("String: " + str);
       Console.WriteLine("Splitted string:");
       foreach (string i in result)
       {
           Console.WriteLine(i);
       }
   }
}

Source Code: Program that splits a string using regular expressions in C#

The output of the above program is as follows:

String: The ocean is blue
Splitted string:
The
ocean
is
blue

Check if a Substring is present in a Given String in C#

A program that checks if a substring is present in a string is given as follows:

using System;
public class Demo
{
public static void Main()
{
 string s1 = "Apple", s2 = "App";
 bool flag;
 flag = s1.Contains(s2);
 if (flag)
  Console.Write("The substring " + s2 + " is in the string " + s1);
 else
  Console.Write("The substring " + s2 + " is not in the string " + s1);
}
}

Source Code: Program that checks if a substring is present in a string in C#

The output of the above program is as follows:

The substring App is in the string Apple

Definition of multiline String Literal in C#

A program that defines the multiline string literal is given as follows:

using System;
namespace Demo
{
  class Example
  {
     static void Main(string[] args)
     {
       string str = @"Hello everyone,
       these are multiline strings in C#";
       Console.WriteLine(str);
     }
  }
}

Source Code: Program that defines the multiline string literal in C#

The output of the above program is as follows:

Hello everyone,
       these are multiline strings in C#

Calculate the length of the string using C#

A program that calculates the length of the string is given as follows:

using System;
using System.Collections;
namespace Demo
{
  class Example
  {
     static void Main(string[] args)
     {
        string str = "It is raining";
        Console.WriteLine("String: " + str);
        Console.WriteLine("String Length: " + str.Length);
     }
  }
}

Source Code: Program that calculates the length of the string in C#

The output of the above program is as follows:

String: It is raining

Concatenation of two strings in C#

A program that concatenates two strings is given as follows:

using System;
class Example
{
   static void Main()
   {
       string str1 = "John";
       string str2 = "Smith";
       string strConcat = string.Concat(str1, str2);
       Console.WriteLine("str1: " + str1);
       Console.WriteLine("str2: " + str1);
       Console.WriteLine("Concatenated String: " + strConcat);
   }
}

Source Code: Program that concatenates two strings in C#

The output of the above program is as follows:

String: It is raining
String Length: 13

Concatenation of two strings in C#

A program that concatenates two strings is given as follows:

using System;
class Example
{
   static void Main()
   {
       string str1 = "John";
       string str2 = "Smith";
       string strConcat = string.Concat(str1, str2);
       Console.WriteLine("str1: " + str1);
       Console.WriteLine("str2: " + str1);
       Console.WriteLine("Concatenated String: " + strConcat);
   }
}

Source Code: Program that concatenates two strings in C#

The output of the above program is as follows:

str1: John
str2: John
Concatenated String: JohnSmith

Usage of the @ prefix on string literals in C#

A program that shows the usage of the @ prefix on string literals is given as follows:

using System;
namespace Demo
{
  class Example
  {
     static void Main(string[] args)
     {
       string str = @"Hello User,
       The image is currently
       loading";
       Console.WriteLine(str);
     }
  }
}

Source Code: Program that shows the usage of the @ prefix on string literals in C#

The output of the above program is as follows:

Hello User,
       The image is currently
       loading

Check if a string contains any special character in C#

A program that checks if a string contains a special character is given as follows:

using System;
namespace Demo
{
   class myApplication
   {
    static void Main(string[] args)
    {
        string str = "String#@!";
        char[] c1 = str.ToCharArray();
        char[] c2 = new char[c1.Length];
          int j = 0;
           for (int i = 0; i < c1.Length; i++)
           {
               if (!Char.IsLetterOrDigit(c1[i]))
               {
                   c2[j] = c1[i];
                   j++;
               }
           }
           Array.Resize(ref c2, j);
           Console.WriteLine("String is: " + str);
           Console.WriteLine("Following are the special characters:");
           foreach(var val in c2)
           {
               Console.WriteLine(val);
           }
    }
   }
}

Source Code: Program that checks if a string contains a special character in C#

The output of the above program is as follows:

String is: String#@!
Following are the special characters:
#
@
!

Check if a string is palindrome or not in C#

A program that checks if a string is palindrome or not is given as follows:

using System;
namespace palindromeDemo
{
   class Example
   {
      static void Main(string[] args)
       {
           string str, revStr;
           str = "madam";
           char[] c = str.ToCharArray();
           Array.Reverse(c);
           revStr = new string(c);
           bool b = str.Equals(revStr, StringComparison.OrdinalIgnoreCase);
           if (b == true)
           {
               Console.WriteLine(str + " is a palindrome");
           }
           else
           {
               Console.WriteLine(str + " is not a palindrome");
           }
       }
   }
}

Source Code: Program that checks if a string is palindrome or not in C#

The output of the above program is as follows:

madam is a palindrome

Add string values to a C# list

A program that adds strings values to a list is given as follows:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
namespace Demo
{
 public class Example
 {
   public static void Main(String[] args)
   {
       List<string> strList = new List<string>();
       strList.Add("Harry");
       strList.Add("John");
       strList.Add("Donald");
       strList.Add("Mary");
       strList.Add("Susan");
       Console.WriteLine("Number of list values are: " + strList.Count);
   }
 }
}

Source Code: Program that adds strings values to a list in C#

The output of the above program is as follows:

Number of list values are: 5

Count the vowels in a string in C#

A program that counts the vowels in a string is given as follows:

using System;  
public class Demo  
{  
   public static void Main()
   {
       string str;
       int i, length, vCount = 0, cCount = 0;
       str = "Beautiful";
       length = str.Length;
       for(i=0; i<length; i++)
       {
           if(str[i] =='a' || str[i]=='e' || str[i]=='i' || str[i]=='o' || str[i]=='u' || str[i]=='A' || str[i]=='E' || str[i]=='I' || str[i]=='O' || str[i]=='U')
           {
               vCount++;
           }
           else
           {
               cCount++;
           }
       }
      Console.Write("Vowels in the string are: {0}", vCount);
}
}

Source Code: Program that counts the vowels in a string in C#

The output of the above program is as follows:

Vowels in the string are: 5

String format for DateTime in C#

A program that demonstrates the DataTime in C# is given as follows:

using System;
static class Demo
{
   static void Main()
   {
       DateTime dt = new DateTime(2015, 8, 2, 12, 4, 9, 123);
       Console.WriteLine(String.Format("{0:y yy yyy yyyy}", dt));
       Console.WriteLine(String.Format("{0:M MM MMM MMMM}", dt));
       Console.WriteLine(String.Format("{0:d dd ddd dddd}", dt));
   }
}

Source Code: Program that demonstrates the DataTime in C#

The output of the above program is as follows:

15 15 2015 2015
8 08 Aug August
2 02 Sun Sunday

Count upper and lower case characters in a given string in C#

A program that counts the upper and lower case characters in a string is given as follows:

using System;  
public class Demo  
{  
   public static void Main()
   {
       string str = "Fish";
       int i, len, lcount = 0, ucount = 0;
       Console.WriteLine("The String is: " + str);
       len = str.Length;
       for(i=0; i<len; i++)
       {
           if(str[i]>='a' && str[i]<='z')
           {
               lcount++;
           }
           else if(str[i]>='A' && str[i]<='Z')
           {
               ucount++;
           }
       }
      Console.WriteLine("Characters in lowercase: {0}", lcount);
      Console.WriteLine("Characters in uppercase: {0}", ucount);
   }
}

Source Code: Program that counts the upper and lower case characters in a string in C#

The output of the above program is as follows:

The String is: Fish
Characters in lowercase: 3
Characters in uppercase: 1

Reverse a String using C#

A program that reverses a string is given as follows:

using System;
namespace Demo
{
  class Example
  {
     static void Main(string[] args)
     {
        string str = "Apple";
        char[] c = str.ToCharArray();
        Array.Reverse(c);
        Console.WriteLine("The string is: " + str);
        Console.Write("The reversed string is: ");
        foreach(var i in c)
           {
               Console.Write(i);
           }
     }
  }
}

Source Code: Program that reverses a string in C#

The output of the above program is as follows:

The string is: Apple
The reversed string is: elppA

Replace a word in a string in C#

A program that replaces a word in a string is given as follows:

using System;
public class Demo
{
   public static void Main()
   {
       string str = "I love dancing";
       Console.WriteLine("Original string: " + str);
       string newStr = str.Replace("dancing", "drawing");
       Console.WriteLine("Edited string: " + newStr);
   }
}

Source Code: Program that replaces a word in a string in C#

The output of the above program is as follows:

Original string: I love dancing
Edited string: I love drawing

Sorting a String in C#

A program that sorts a string in C# is given as follows:

using System;
public class Example
{
   public static void Main()
   {
        string[] str = { "John", "Sally", "Harry", "Peter", "Susan"};
Console.WriteLine("Initial values: ");
        foreach (string val in str)
        {
           Console.Write(val);
           Console.Write(" ");
        }
       Array.Sort(str);
Console.WriteLine();
       Console.WriteLine("Sorted values: ");
       foreach (string val in str)
       {
           Console.Write(val);
           Console.Write(" ");
       }
   }
}

Source Code: Program that sorts a string in C#

The output of the above program is as follows:

Initial values:
John Sally Harry Peter Susan
Sorted values:
Harry John Peter Sally Susan

Find the first 10 characters of a string in C#

A program that finds the first 10 characters of a string in C# is given as follows:

using System;
public class Demo
{
public static void Main()
{
   string str = "Cricket is a famous sport";
   string substr = str.Substring(0, 10);
   Console.WriteLine("String: " + str);
   Console.WriteLine("Substring: " + substr);
}
}

Source Code: Program that finds the first 10 characters of a string in C#

The output of the above program is as follows:

String: Cricket is a famous sport
Substring: Cricket is

Find the first character of a string in C#

A program that finds the first character of a string in C# is given as follows:

using System;
public class Demo
{
public static void Main()
{
   string str = "Mangoes!";
   string fChar = str.Substring(0, 1);
   Console.WriteLine("String: " + str);
   Console.WriteLine("First character: " + fChar);
}
}

Source Code: Program that finds the first character of a string in C#

The output of the above program is as follows:

String: Mangoes!
First character: M
+91

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