C# Programs

Reverse a number

 class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Enter a Number");
            int numb = int.Parse(Console.ReadLine());
            int reverse = 0;
            while (numb > 0)
            {
                int rem = numb % 10;
                reverse = (reverse * 10) + rem;
                numb = numb / 10;
              
            }
            Console.WriteLine("Reverse number={0}", reverse);
            Console.ReadLine();
        }

    }

Output
----------
Enter a Number
4567
Reverse number=7654


Palindrome Program

class program
{
    public static void Main()
    {
        int num, temp, remainder, reverse = 0;
        Console.WriteLine("Enter an integer \n");
        num = int.Parse(Console.ReadLine());
        temp = num;
        while (num > 0)
        {
            remainder = num % 10;
            reverse = reverse * 10 + remainder;
            num /= 10;
        }
        Console.WriteLine("Given number is = {0}", temp);
        Console.WriteLine("Its reverse is  = {0}", reverse);
        if (temp == reverse)
            Console.WriteLine("Number is a palindrome \n");
        else
            Console.WriteLine("Number is not a palindrome \n");
        Console.ReadLine();
    }
}

//Output--535 is a prime number(if its reverse also 535 only)

Armstrong Number

An Armstrong number of three digits is an integer such that the sum of the cubes of its digits is equal to the number itself.

class Program
    {
        static void Main(string[] args)
        {
            int number, remainder, sum = 0;
            Console.Write("enter the Number");
            number = int.Parse(Console.ReadLine());
            for (int i = number; i > 0; i = i / 10)
            {
                remainder = i % 10;
                sum = sum + remainder*remainder*remainder;

            }
            if (sum == number)
            {
                Console.Write("Entered Number is an Armstrong Number");
            }
            else
                Console.Write("Entered Number is not an Armstrong Number");
            Console.ReadLine();
        }
     }

Output
----------
Enter the Number : 371

Entered Number is an Armstrong Number

Explantion:3Cube+7cube+1cube=371

Sum of given Number

static void Main(string[] args)
        {
            int num, sum = 0, r;
            Console.WriteLine("Enter a Number : ");
            num = int.Parse(Console.ReadLine());
            while (num != 0)
            {
                r = num % 10;
                num = num / 10;
                sum = sum + r;
            }
            Console.WriteLine("Sum of Digits of the Number : "+sum);
            Console.ReadLine();

        }
//Output--Enter a Number : 123
//Sum of Digits of the Number : 6
          

Prime Numbers Between 1 to 10

class Program
{
    static void Main(string[] args)
    {
        bool isPrime = true;
        Console.WriteLine("Prime Numbers : ");
        for (int i = 2; i <= 10; i++)
        {
            for (int j = 2; j <= 10; j++)
            {

                if (i != j && i % j == 0)
                {
                    isPrime = false;
                    break;
                }

            }
            if (isPrime)
            {
                Console.Write("\t" + i);
            }
            isPrime = true;
        }
        Console.ReadKey();
    }

}


//output--2 3 5 7


strong number 
A number is called strong number if sum of the factorial of its digit is equal to number itself.
Ex : 1! + 4! + 5! = 1 + 24 + 120 = 145

Code:
static void Main(string[] args)
{
Int32 num, i, f, r, sum = 0, temp;

Console.WriteLine("enter the number");
num = Convert.ToInt16((Console.ReadLine()));
temp=num;
while (num != 0)
{
   i = 1; f = 1;

   r = num % 10;
     while (i <= r)
     {
        f = f * i;
        i++;
     }

sum = sum + f;
num = num / 10;
}
if (sum == temp)
Console.WriteLine("Strong No", temp);

else
Console.WriteLine("not Strong NO", temp); 

Console.ReadLine();

}

Number sort

int temp = 0;
        int[] arr = new int[] { 20, 65, 98, 71, 64, 11, 2, 80, 5, 6, 100, 50, 13, 9, 80, 454 };
        for (int i = 0; i < arr.Length; i++)
        {
            for (int j = i + 1; j < arr.Length; j++)
            {
                if (arr[i] > arr[j])
                {
                    temp = arr[j];
                    arr[j] = arr[i];
                    arr[i] = temp;
                }
            }
            Console.WriteLine(arr[i]);
        }

string reverse
static void Main(string[] args)
    {
        string Str, reversestring = "";
        int Length;
        Console.Write("Enter A String : ");
        Str = Console.ReadLine();
        Length = Str.Length - 1;
        while (Length >= 0)
        {
            reversestring = reversestring + Str[Length];
            Length--;
        }
        Console.WriteLine("Reverse  String  Is  {0}", reversestring);
        Console.ReadLine();
    }

collasition?

swap even and odd characters in a string

static void Main(string[] args)
        {
            string input = "Gupta"; //Sample String
            // O/P--uGtpa
            StringBuilder output = new StringBuilder();

            char[] characters = input.ToCharArray();

            for (int i = 0; i < characters.Length; i++)
            {
                if (i % 2 == 0)
                {
                    if ((i + 1) < characters.Length)
                    {
                        output.Append(characters[i + 1]);
                    }
                    output.Append(characters[i]);
                }
            }

            Console.WriteLine(output);
            Console.ReadLine();
        }

 

 remove duplicate characters from string.

 void removeDuplicate()
    {
      string value1 = RemoveDuplicateChars("Devarajan");
    }

     static string RemoveDuplicateChars(string key)
    {

        string table = "";
        string result = "";          
        foreach (char value in key)
        {
            if (table.IndexOf(value) == -1)
            {
                table += value;
                result += value;
            }
        }
        return result;
    }

Number of occurrences in a given string

 static void Main(string[] args)
        {
            string input = "ABCA";
            while (input.Length > 0)
            {
                Console.Write(input[0] + " : ");
                int count = 0;
                for (int j = 0; j < input.Length; j++)
                {
                    if (input[0] == input[j])
                    {
                        count++;
                    }
                }
                Console.WriteLine(count);
                input = input.Replace(input[0].ToString(), string.Empty);
            }
            Console.ReadLine();
        }
        //O/P
        //A-2
        //B-1
        //C-1