C# Logical Questions with Answer

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:

public static void ExchangeInteger()
{
    int a = 10;
    int b = 5;
    Console.WriteLine("a={0}", a);
    Console.WriteLine("b={0}", b);
    a = a + b; // Now a would be 15
    b = a - b; // Now b would be 15-5=10 ........
    a = a - b; // Now a would be 15-10=5........
    Console.WriteLine("a={0}", a);
    Console.WriteLine("b={0}", b);
    Console.ReadLine();
}

Calling above method,

static void Main(string[] args)
{
  clsExchangevariable.ExchangeInteger();
}

Output

 

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



Answer:

public static string SwapNeighbourChar(string strToSwap)
{
    char[] arraStr = strToSwap.ToCharArray();
    StringBuilder strbuild = new StringBuilder();
    for (int i = 0; i <= arraStr.Length - 1; i++)
    {
        if (i != arraStr.Length - 1)
        {
            strbuild.Append(arraStr[i + 1]);
        }
        strbuild.Append(arraStr[i]);
        i = i + 1;
    }
    return strbuild.ToString();
}

Calling above method

static void Main(string[] args)
{
     Console.WriteLine(clsSwapNeighbour.SwapNeighbourChar("TAPAN"));
     Console.ReadLine();
}

Output



Question 3: Is prime number?

Answer:

public static bool IsPrimeNumbers(int number)
{
    bool returnMsg = false;
    for (int i = 2; i <= number; i++)
    {
        if ((number % i) == 0 && number != i)
        {
            returnMsg = false;
            return returnMsg;
        }
        else if (number == i)
        {
            returnMsg = true;
            return returnMsg;
        }
    }
    return returnMsg;
}

Calling above method,

static void Main(string[] args)
{
    string message = clsIsPrimeNumber.IsPrimeNumbers(17) == true ? "Prime Number" : "Not a prime number";
    Console.WriteLine(message);
    message = clsIsPrimeNumber.IsPrimeNumbers(4) == true ? "Prime Number" : "Not a prime number";
    Console.WriteLine(message);
    message = clsIsPrimeNumber.IsPrimeNumbers(11) == true ? "Prime Number" : "Not a prime number";
    Console.WriteLine(message);
    message = clsIsPrimeNumber.IsPrimeNumbers(21) == true ? "Prime Number" : "Not a prime number";
    Console.WriteLine(message);
    Console.ReadLine();
}

Output:



Question 4: Fibonacci series.

Answer:

public static void PrintFibonacciSeries(int limit)
{
    int digit1, digit2, digit3;
    digit1 = 0;
    digit2 = 1;
    digit3 = digit1 + digit2;
    Console.WriteLine(digit1);
    Console.WriteLine(digit2);
    Console.WriteLine(digit3);
    for (int i = 0; i < limit; i++)
    {
        digit1 = digit2;
        digit2 = digit3;
        digit3 = digit1 + digit2;
        Console.WriteLine(digit3);
    }
}

Calling above method,

static void Main(string[] args)
{
  clsFibonacci.PrintFibonacciSeries(10);
  Console.ReadLine();
}

Output:



Question 5: Get Factorial of number.

Answer:

public static int PrintFactorialOfNumber(int number)
{
    // 7*6
    int result = 1;
    for (int i = number; i > 0; i--)
    {
        result = result * i;
    }
    return result;
}

Calling above method:

static void Main(string[] args)
{
    int factorial;
    factorial = clsfactorial.PrintFactorialOfNumber(5);
    Console.WriteLine("Factorial Of 5 Is " + factorial.ToString());
    factorial = clsfactorial.PrintFactorialOfNumber(7);
    Console.WriteLine("Factorial Of 7 Is " + factorial.ToString());
    Console.ReadLine();
}

Output: