Reverse String in C#

Reverse is used to reverse a string or a number from back to front like for string educba the reverse string is abcude. For number 9436 reverse is 6349. With the help of a reverse string, we can reverse any string. We can implement this method in many ways. Every method has its log(n). Some methods are faster than the other method.

Some methods use more lines of code and are complex in nature which are sometimes hard to understand. We can also reverse the number.

Methods

Here are few methods by using them we can reverse the string:

• Using ReverseString method.
• Using ToCharArray method.
• Programmatically Approach: By using this approach first we will store the string in any variable and then calculate the length of that variable or string. Then we pick one character at one time and can print from starting from the backside or reverse side. Before using this method, we should ensure that this approach should not affect the performance of the program.

So we can use any of the above approaches depending upon the requirements.

Examples of Reverse String in C#

Given below are the examples of Reverse String in C#:

Example #1

Code:

using System ;
using System.Collections.Generic ;
using System.Linq ;
using System.Text ;
using System.Threading.Tasks ;
namespace ReverseString
{
class Program
{
static void Main(string[] args)
{
string Str, rev;
Str = "Programming" ;
rev = "";
Console.WriteLine("Value of given String is: {0}", Str) ;
// find string length
int a;
a = Str.Length - 1 ;
while (a >= 0)
{
rev = rev + Str[a] ;
a--;
}
Console.WriteLine("Reversed string is: {0}", rev) ;
Console.ReadLine() ;
}
}
}

In the above program, Str is used as a variable to store the value of a string. While loop is used to reverse the string and the logic behind is to change the position of characters one by one from right to left.
Output:

Example #2

Code:

using System ;
using System.Collections.Generic;
using System.Linq ;
using System.Text ;
using System.Threading.Tasks ;
static class StringHelper
{
public static string ReverseString(string str)
{
char[] array = str.ToCharArray() ;
Array.Reverse(array) ;
return new string(array) ;
}
}
class Program
{
static void Main()
{
Console.WriteLine(StringHelper.ReverseString("This")) ;
Console.WriteLine(StringHelper.ReverseString("is")) ;
Console.WriteLine(StringHelper.ReverseString("C#")) ;
Console.WriteLine(StringHelper.ReverseString("programming")) ;
Console.ReadLine();
}
}

In the above example, the ReverseString method is used to get the value of string which needs to be reversed Array. The reverse is used for the modification of the order of the characters.

Output:

Example #3

Code:

using System;
using System.Collections.Generic ;
using System.Linq ;
using System.Text ;
using System.Threading.Tasks ;
namespace reverseString
{
class Program
{
static void Main(string[] args)
{
string s = "", rev = "" ;
int len = 0 ;
Console.WriteLine("Enter a string") ;
s = Console.ReadLine();
len = s.Length - 1;
while (len >= 0)
{
rev = rev + s[len] ;
len--;
}
Console.WriteLine("Reverse of string is {0}", rev) ;
Console.ReadLine();
}
}
}

In the above program, we are taking input from the user to reverse the string. A variable is used to store the value of a string. While loop is used to reverse the string and the logic behind is to change the position of characters one by one from right to left.

Output:

Example #4

Code:

using System;
using System.Collections.Generic ;
using System.Linq ;
using System.Text ;
using System.Threading.Tasks ;
namespace reverseString
{
class Program
{
static void Main(string[] args)
{
string s;
Console.Write(" Enter the string : ") ;
s = Console.ReadLine();
s = StringReverse(s);
Console.Write(" Reverse is : ") ;
Console.Write(s) ;
Console.ReadLine() ;
}
public static string StringReverse(string s)
{
if (s.Length > 0)
return s[s.Length - 1] + StringReverse(s.Substring(0, s.Length - 1)) ;
else
return s ;
}
}
}

Output:

Example #5

Code:

using System ;
using System.Collections.Generic ;
using System.Linq ;
using System.Text ;
using System.Threading.Tasks ;
namespace reverseString
{
class Program
{
public static void Main()
{
Console.WriteLine(reverse("Hello")) ;
Console.ReadLine();
}
public static string reverse(string s)
{
string reverseStr = "" ;
for (int a = s.Length - 1; a >= 0; a--)
{
reverseStr = reverseStr + s[a] ;
}
return reverseStr ;
}
}
}

In the above example, for loop is used to reverse the given string.

Output:

Example #6

Code:

using System ;
using System.Collections.Generic ;
using System.Linq ;
using System.Text ;
using System.Threading.Tasks ;
namespace reverseString
{
class Program
{
public static void Main()
{
string s;
Console.WriteLine("The value of given string is ") ;
s = Console.ReadLine() ;
char[] array = s.ToCharArray() ;
Array.Reverse(array);
Console.WriteLine(new String(array)) ;
Console.ReadLine() ;
}
}
}

Output:

Conclusion

So we can reverse any given string or number by using the number of approaches. But we should ensure that our choice should not affect the performance because each method has its own time complexity.

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