Help4Code | Online eLearning

C#.NET TECHNICAL QUESTIONS

1. Which of the following statements are correct about the C#.NET code snippet given below?

            class Sample
            {
                static int i;
                int j;
                public void proc1()
                {
                    i = 11;
                    j = 22;
                }
                public static void proc2()
                {
                    i = 1;
                    j = 2;
                }
                static Sample()
                {
                    i = 0;
                    j = 0;
                }
            }
            (A) j can be initialized in proc2().
            (B) i cannot be initialized in proc1().
            (C) proc1() can initialize i as well as j.
            (D) proc2() can initialize i as well as j.

Answer : proc1() can initialize i as well as j.

2. Which of the following statements is correct about the C#.NET program given below?

            namespace PskillsConsoleApplication
            {
                class Baseclass
                {
                    int i;
                    public Baseclass(int ii)
                    {
                        i = ii;
                        Console.Write("Base ");
                    }
                }
                class Derived : Baseclass
                {
                    public Derived(int ii) : base(ii)
                    {
                        Console.Write("Derived ");
                    }
                }
                class MyProgram
                {
                    static void Main(string[ ] args)
                    {
                        Derived d = new Derived(10);
                    }
                }
            }
            (A) The program will report an error in the statement base(ii).
            (B) The program will work correctly if we replace base(ii) with base.Baseclass(ii).
            (C) The program will output: Base Derived
            (D) The program will work correctly only if we implement zero-argument constructors in Baseclass as well as Derived class.

Answer : The program will output: Base Derived

3. Which Gang of Four design pattern is shown below?

            public class A {
            private A instance;
            private A() {
            }
            public
            static A Instance {
            get
            {
            if ( A == null )
            A = new A();
            return instance;
            }
            }
            }
            (A) Abstract Factory
            (B) Singleton
            (C) Builder
            (D) Factory

Answer : Singleton

4. Which of the following statements is correct about the C#.NET code snippet given below?

        namespace PskillsConsoleApplication
        {
            class Sample
            {
                public int func()
                {
                    return 1;
                }
                public Single func()
                {
                    return 2.4f ;
                }
            }
            class Program
            {
                static void Main(string[ ] args)
                {
                    Sample s1 = new Sample();
                    int i;
                    i = s1.func();
                    Single j;
                    j = s1.func();
                }
            }
        }
        (A) func() is a valid overloaded function.
        (B) func() cannot be considered overloaded because: return value cannot be used to distinguish between two overloaded functions.
        (C) Overloading works only in case of subroutines and not in case of functions.
        (D) The call j = s1.func() will assign 2.4 to j.

Answer : func() cannot be considered overloaded because: return value cannot be used to distinguish between two overloaded functions.

5. Which of the following ways to create an object of the Sample class given below will work correctly?

            class Sample
            {
                int i;
                Single j;
                double k;
                public Sample (int ii, Single jj, double kk)
                {
                    i = ii;
                    j = jj;
                    k = kk;
                }
            }
            (A) Sample s3 = new Sample(10, 1.2f, 2.4);
            (B) Sample s2 = new Sample(10, 1.2f);
            (C) Sample s1 = new Sample(, , 2.5);
            (D) Sample s1 = new Sample(10);

Answer : Sample s3 = new Sample(10, 1.2f, 2.4);

6. Which of the following statements are correct about the C#.NET code snippet given below?

            class Sample
            {
                static int i;
                int j;
                public void proc1()
                {
                    i = 11;
                    j = 22;
                }
                public static void proc2()
                {
                    i = 1;
                    j = 2;
                }
                static Sample()
                {
                    i = 0;
                    j = 0;
                }
            }
            (A) j can be initialized in proc2().
            (B) i cannot be initialized in proc1().
            (C) proc1() can initialize i as well as j.
            (D) proc2() can initialize i as well as j.

Answer : proc1() can initialize i as well as j.

7. Write a program to show difference between value type parameter and refere

            using System;

            namespace Example1
            {
            class Program
                {
                public static void value(int num)
                {
                    num++;
                }
                public static void reference(ref int num)
                {
                    num++;
                }

                static void Main(string[] args)
                {
                    int num;
                    Console.Write("Enter a number:\t");
                    num = Convert.ToInt32(Console.ReadLine());
                    Console.WriteLine("\n\n\tValue Type");
                    Console.WriteLine("----------------");
                    Console.Write("\nPrevious Value:\t{0}", num);
                    Program.value(num);
                    Console.Write("\nCurrent Value:\t{0}", num);

                    Console.WriteLine("\n\n\n----------------");
                    Console.WriteLine("\tReference Type");
                    Console.WriteLine("--------------------");
                    Console.Write("\nPrevious Value:\t{0}", num);
                    Program.reference(ref num);
                    Console.Write("\nCurrent Value:\t{0}", num);
                    Console.ReadLine();
                }
                }
            }

Output :
Enter a number: 9
Value Type
---------------------------------
Previous Value: 9
Current Value: 9
---------------------------------
Reference Type
---------------------------------
Previous Value: 9
Current Value: 10

8. Write a program in which accept two argument as parameter from the user and returns four output value as add, subtract, multiplication and division.

        using System;

        namespace Example2
        {
            class Program
            {
            public static void parameter(int num1, int num2,            out int add, out int sub, out int mul, out float div)
                {
                add = num1 + num2;
                sub = num1 - num2;
                mul = num1 * num2;
                div = (float)num1 / num2;
                }
            static void Main(string[] args)
                {
                int num1,num2;
                int add, sub, mul;
                float div;
                Console.Write("Enter 1st number\t");
                num1 = Convert.ToInt32(Console.ReadLine());
                Console.Write("\nEnter 2nd number\t");
                num2 = Convert.ToInt32(Console.ReadLine());

                Program.parameter(num1, num2, out add, out sub,              out mul, out div);
                Console.WriteLine("\n\n{0} + {1} = {2}", num1,              num2, add);
                Console.WriteLine("{0} - {1} = {2}", num1, num2,            sub);
                Console.WriteLine("{0} * {1} = {2}", num1, num2,            mul);
                Console.WriteLine("{0} / {1} = {2}", num1, num2,            div);

                Console.ReadLine();
                }
            }
        }

Output :
Enter 1st number 7
Enter 2nd number 9
7 +9 = 16
7 - 9 = -2
7 * 9 = 63
7 / 9 = 0.7777778

9. What is the output of the short program below? Explain your answer.

        class Program {
        static String location;
        static DateTime time;

        static void Main() {
            Console.WriteLine(location == null ? "location is null" : location);
            Console.WriteLine(time == null ? "time is null" : time.ToString());
        }
        }

Answer The output will be:
location is null
1/1/0001 12:00:00 AM

10. What is the output of the program below? Explain your answer.

        delegate void Printer();

        static void Main()
        {
            List printers = new List();
            for (int i = 0; i < 10; i++)
            {
                    printers.Add(delegate { Console.WriteLine(i); });
            }

            foreach (var printer in printers)
            {
                    printer();
            }
        }

Answer : This program will output the number 10 ten times.
Here’s why: The delegate is added in the for loop and “reference” (or perhaps “pointer”
would be a better choice of words) to i is stored, rather than the value itself.
Therefore, after we exit the loop, the variable i has been set to 10, so by the time each delegate is invoked, the value passed to all of them is 10.