I would be very happy if someone will provide better solution for these questions -

Question 1: Exchange Two integer variable value without using third variable.

Answer:

  1. public static void ExchangeInteger()
  2. {
  3. int a = 10;
  4. int b = 5;
  5. Console.WriteLine("a={0}", a);
  6. Console.WriteLine("b={0}", b);
  7. a = a + b; // Now a would be 15
  8. b = a - b; // Now b would be 15-5=10 ........
  9. a = a - b; // Now a would be 15-10=5........
  10. Console.WriteLine("a={0}", a);
  11. Console.WriteLine("b={0}", b);
  12. Console.ReadLine();
  13. }
Calling above method,
  1. static void Main(string[] args)
  2. {
  3. clsExchangevariable.ExchangeInteger();
  4. }
Output

Exchange Two integer variable value

Question 2: Swap neighbor char in string, For Example string “TAPAN” would be:

neighbor char in string

Answer:

  1. public static string SwapNeighbourChar(string strToSwap)
  2. {
  3. char[] arraStr = strToSwap.ToCharArray();
  4. StringBuilder strbuild = new StringBuilder();
  5. for (int i = 0; i <= arraStr.Length - 1; i++)
  6. {
  7. if (i != arraStr.Length - 1)
  8. {
  9. strbuild.Append(arraStr[i + 1]);
  10. }
  11. strbuild.Append(arraStr[i]);
  12. i = i + 1;
  13. }
  14. return strbuild.ToString();
  15. }
Calling above method
  1. static void Main(string[] args)
  2. {
  3. Console.WriteLine(clsSwapNeighbour.SwapNeighbourChar("TAPAN"));
  4. Console.ReadLine();
  5. }
Output

Swap neighbor char in string

Question 3: Is prime number?

Answer:
  1. public static bool IsPrimeNumbers(int number)
  2. {
  3. bool returnMsg = false;
  4. for (int i = 2; i <= number; i++)
  5. {
  6. if ((number % i) == 0 && number != i)
  7. {
  8. returnMsg = false;
  9. return returnMsg;
  10. }
  11. else if (number == i)
  12. {
  13. returnMsg = true;
  14. return returnMsg;
  15. }
  16. }
  17. return returnMsg;
  18. }
Calling above method,
  1. static void Main(string[] args)
  2. {
  3. string message = clsIsPrimeNumber.IsPrimeNumbers(17) == true ? "Prime Number" : "Not a prime number";
  4. Console.WriteLine(message);
  5. message = clsIsPrimeNumber.IsPrimeNumbers(4) == true ? "Prime Number" : "Not a prime number";
  6. Console.WriteLine(message);
  7. message = clsIsPrimeNumber.IsPrimeNumbers(11) == true ? "Prime Number" : "Not a prime number";
  8. Console.WriteLine(message);
  9. message = clsIsPrimeNumber.IsPrimeNumbers(21) == true ? "Prime Number" : "Not a prime number";
  10. Console.WriteLine(message);
  11. Console.ReadLine();
  12. }
Output:

s prime number

Question 4: Fibonacci series.

Answer:
  1. public static void PrintFibonacciSeries(int limit)
  2. {
  3. int digit1, digit2, digit3;
  4. digit1 = 0;
  5. digit2 = 1;
  6. digit3 = digit1 + digit2;
  7. Console.WriteLine(digit1);
  8. Console.WriteLine(digit2);
  9. Console.WriteLine(digit3);
  10. for (int i = 0; i < limit; i++)
  11. {
  12. digit1 = digit2;
  13. digit2 = digit3;
  14. digit3 = digit1 + digit2;
  15. Console.WriteLine(digit3);
  16. }
  17. }
Calling above method,
  1. static void Main(string[] args)
  2. {
  3. clsFibonacci.PrintFibonacciSeries(10);
  4. Console.ReadLine();
  5. }
Output:

ibonacci series

Question 5: Get Factorial of number.

Answer:
  1. public static int PrintFactorialOfNumber(int number)
  2. {
  3. // 7*6
  4. int result = 1;
  5. for (int i = number; i > 0; i--)
  6. {
  7. result = result * i;
  8. }
  9. return result;
  10. }
Calling above method:
  1. static void Main(string[] args)
  2. {
  3. int factorial;
  4. factorial = clsfactorial.PrintFactorialOfNumber(5);
  5. Console.WriteLine("Factorial Of 5 Is " + factorial.ToString());
  6. factorial = clsfactorial.PrintFactorialOfNumber(7);
  7. Console.WriteLine("Factorial Of 7 Is " + factorial.ToString());
  8. Console.ReadLine();
  9. }
Output:
Get Factorial of number