C# Multiple Choice Questions & Answers on Initialization of Variables for Freshers

1. Select output for the following set of code.

1.  static void Main(string[] args)

2.  {

3.      int a = 5;

4.      int b = 10;

5.      int c;

6.      Console.WriteLine(c = ++ a + b ++);

7.      Console.WriteLine(b);

8.      Console.ReadLine();

9.  }

a) 11, 10
b) 16, 10
c) 16, 11
d) 15, 11

Answer: c

Explanation : c = 6 + 10 = 16 and b =11 as we know ++operator increments and then executes similarly operator++ executes and then increments.

2. Storage location used by computer memory to store data for usage by an application is ?

a) Pointers
b) Constants
c) Variable
d) None of the mentioned

Answer: c

Explanation : ‘Variables’ are essential locations in memory of computer that are reserved for storing data used by an application. Each variable is given a name by programmer and hence assigned a value .The name assigned to variable then used in C# code to access value assigned to variable.

3. DIFFERENCE BETWEEN KEYWORDS ‘VAR’ AND ‘DYNAMIC’ ?

a) ‘Var’ is introduced in C# (3.0) and ‘Dynamic’ is introduced in C# (4.0)
b) ‘Var’ is a type of variable where declaration is done at compile time by compiler while ‘Dynamic’ declaration is achieved at runtime by compiler
c) For ‘Var’ Error is caught at compile time and for ‘Dynamic’ Error is caught at runtime
d) All of the mentioned

Answer: d

4. Are the given codes :

1.  1. Myclass class;

2.     Myclass class2 = null;

1.  2. int i;

2.     int j = 0;

a) True for (1);False for (2)
b) True for (2);False for (1)
c) Both (1) and (2) are equivalents
d) Both (1) and (2) are not equivalents

Answer: c.

Explanation : When we create a type in ‘C#’, It automatically gets filled with padded zeroes. For the case of class (reference types) this equates to a null pointer. Hence, for code 1) Both variable values are equivalent to each other.Similarly, for code 2) i.e for value type (including int/float/double etc.), the type is passed with zeroes.Hence, they are equivalent.

5. What is the output of following set of code ?

1.   int a,b;

2.   a = (b = 10) + 5;

a) b = 10, a = 5
b) b = 15, a = 5
c) a = 15, b = 10
d) a = 10, b = 10

Answer: c

Explanation: b is assigned 10 and after that its value is added with 5 and then saved in a, so a will be 15.

6. What will be output of the following conversion ?

1.  static void Main(string[] args)

2.  {

3.      char a = 'A';

4.      string b = "a";

5.      Console.WriteLine(Convert.ToInt32(a));

6.      Console.WriteLine(Convert.ToInt32(Convert.Tochar(b)));

7.      Console.ReadLine();

8.  }

a) 1, 97
b) 65, 97
c) 65, 97
d) 97, 1

Answer: c

Explanation : ASCII value of character ‘a’ is 65 and ASCII value of string “a” is 97.

7. Select output of the given set of Code :

1. static void Main(string[] args)

2. {

3.     String name = "Dr.Gupta";

4.     Console.WriteLine("Good Morning" + name);

5. }

a) Dr.Gupta
b) Good Morning
c) Good Morning Dr.Gupta
d) Good Morning name

Answer: c.

Explanation:How to intialize a string variable and concatenate string using ‘+’ operator.

8. Select output for the following set of code.

1.  static void Main(string[] args)

2.  {

3.      int a = 5;

4.      int b = 10;

5.      int c;

6.      Console.WriteLine(c = a-- - ++b);

7.      Console.WriteLine(b);

8.      Console.ReadLine();

9.  }

a) -7, 10
b) -5, 11
c) -6, 11
d) 15, 11

Answer: c

9. Select output for the following set of code .

1.  static void Main(string[] args)

2.  {

3.      const int a = 5;

4.      const int b = 6;

5.      for (int i = 1; i <= 5; i++)

6.      {

7.          a = a * i;

8.          b = b * i;

9.      }

10.      Console.WriteLine(a);

11.      Console.WriteLine(b);

12.      Console.ReadLine();

13.  }

a) 600, 720
b) Compile time error.
c) 25, 30
d) 5, 6

Answer: b

Explanation:The left hand side of an assignment must be a variable,property or indexer i.e for both ‘a’ and ‘b’

10. Select output for the following set of code.

1.  static void Main(string[] args)

2.  {

3.      string Name = "He is playing in a ground.";

4.      char[] characters = Name.ToCharArray();

5.      StringBuilder sb = new StringBuilder();

6.      for (int i = Name.Length - 1; i >= 0; --i)

7.      {

8.          sb.Append(characters[i]);

9.      }

10.      Console.Write(sb.ToString());

11.      Console.ReadLine(); 

12.  }

a) He is playing in a grou
b) .ground a in playing is He
c) .dnuorg a ni gniyalp si eH
d) He playing a

Answer: c

Explanation:Reversal of array of strings character by character.