Strings in C#

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:

Table: Constructors in String in C#

Source: MSDN

String Properties

The different properties and their description is given as follows:

Table: Properties in String in C#

Source: MSDN

String Methods

The different methods and their description is given as follows:

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:

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

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);
     }
  }
}

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:

Source Code: Program to compare two strings in C#

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");
        }
     }
  }
}

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:

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

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);
}
}

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:

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

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*$"));
}
}

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:

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

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]");
     }
  }
}

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:

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

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));
 }
}
}

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:

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

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);
   }
}

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:

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

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);
        }
     }
  }
}

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:

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

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);
       }
   }
}

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:

Source Code: Program to match all the digits in a string in C#

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:

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

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);
     }
  }
}

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:

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

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);
     }
  }
}

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:

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

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);   
     }
  }
}

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:

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

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());
   }
}

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:

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

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);
       }
}

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:

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

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);
       }
   }
}

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:

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

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);
       }
   }
}

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:

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

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);
}
}

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:

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

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

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:

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

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);
     }
  }
}

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:

Source Code: Program that concatenates two strings in C#

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);
   }
}

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:

Source Code: Program that concatenates two strings in C#

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);
   }
}

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:

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

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

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:

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

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);
           }
    }
   }
}

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:

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

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");
           }
       }
   }
}

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:

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

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);
   }
 }
}

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:

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

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);
}
}

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:

Source Code: Program that demonstrates the DataTime in C#

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));
   }
}

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:

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

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);
   }
}

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:

Source Code: Program that reverses a string in C#

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);
           }
     }
  }
}

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:

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

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);
   }
}

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:

Source Code: Program that sorts a string in C#

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(" ");
       }
   }
}

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:

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

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);
}
}

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:

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

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);
}
}

The output of the above program is as follows:

String: Mangoes!
First character: M