C# Questions & Answers on Pointers Operation – 1 for Freshers

1. What will be the output of the given code?

1.  class UnsafeCode

2.  {

3.      unsafe static void Main()

4.      {

5.          int m = 10;

6.          int *mptr = &m;

7.          int **ptr = &mptr;

8.          int n = 20;

9.          int *nptr = &n;

10.          int **prt = &nptr;

11.          m = **prt + *nptr;

12.          n = *mptr* **prt;

13.          Console.WriteLine(n + " " + m);

14.          Console.ReadLine();

15.      }

16.  }

a) 20 200
b) 40 200
c) 800 40
d) 40 800

Answer: c

Output: 800 40

2. What will be the output of the code snippet?

1.  unsafe static void Main()

2.  {

3.      int a = 5;

4.      int b = 5;

5.      int c = 5;

6.      int*[] ptr = new int* [3];

7.      ptr[0] = &a;

8.      ptr[1] = &b;

9.      ptr[2] = &c;

10.      for (a = 0; a < 3; a++)

11.      {

12.          c += *ptr[a];

13.          Console.WriteLine(c);

14.      }

15.      Console.ReadLine();

16.  }

a) 5 10
b) 10 20
c) Compile time error
d) 5 10 20

Answer: d

Output:5 10 20

3. What will be the output of the code snippet?

1. class UnsafeCode

2. {

3.     unsafe static void Main()

4.     {

5.         int* ptrs = stackalloc int[3];

6.         ptrs[0] = 1;

7.         ptrs[1] = 2;

8.         ptrs[2] = 3;

9.         for (int i = 2; i >= 0; --i)

10.         {

11.             ptrs[i] = ptrs[i]* 3;

12.             ptrs[i] = ptrs[i] + 4;

13.             Console.WriteLine(ptrs[i]);

14.         }

15.         Console.ReadLine();

16.     }

17. }

a) 20, 10, 7
b) 13, 10, 7
c) 6, 9, 3
d) Compile time error

Answer: b

Output: 13, 10, 7

4. Among the given pointers which of following cannot be incremented?

a) int
b) char
c) float
d) void

Answer: d

5. A structure pointer points to __________

a) first member of structure
b) first two members of structure
c) whole structure
d) only to the last member of structure

Answer: c

6. What will be the declaration of the variable ptr as the pointer to array of 6 floats?

a) float *ptr[6].
b) float [6]*ptr
c) float(*ptr)[6].
d) float(*ptr)(6).

Answer: c

7. what will be the output of code snippet?

1.  class UnsafeCode

2.  {

3.      unsafe static void Main()

4.      {

5.          char[] arr = { 'A', 'B', 'C', 'D', 'E' };

6.          fixed (char* P = arr)

7.          {

8.              int i;

9.              for (i = 0 ;i < 5 ;i++)

10.              if (*P % 2 == 0)

11.              ++*P;

12.              else

13.              (*P)++;

14.              Console.WriteLine(arr);

15.          }

16.          Console.ReadLine();

17.      }

18.  }

a) ACCEE
b) FBCDE
c) BBDDF
d) BBCEE

Answer: b

Output:FBCDE

8. What will be the output of given code snippet?

1. class UnsafeCode

2.  {

3.      unsafe static void Main()

4.      { 

5.          int[] nums = new int[10];

6.          Console.WriteLine("Index pointer like array.");

7.          fixed (int* p = nums)

8.          {

9.              for (int i = 0 ;i <10 ;i++)

10.              p[i] = i;

11.              for (int i = 10 ;i >0 ;i--)

12.              Console.WriteLine("p[{0}]: {1} ", i, p[i]);

13.              Console.ReadLine();

14.          }

15.      }

16.  }

a) p[10] :0, p[9] :9, p[8] :8…..p[1]:1
b) p[10] : 1, p[9] :2, p[8] :3…..p[1] :0
c) p[1] : 1, p[2] :2, p[3] :3…..p[10] :0
d) Compile time error

Answer: a

Output:Index pointer like array:
p[10] :0, p[9] :9, p[8] :8…p[1]:1

9. What will be the output of the given code snippet?

1.  class UnsafeCode

2.  {

3.      unsafe static void Main()

4.      {

5.          string str = "this is a test";

7.              fixed (char* p = str)

8.             {

9.                 for (int i = str.Length-1 ;p[i] != 0 ;i--)

10.                 Console.Write(p[i]);

11.             }

12.         Console.ReadLine();

13.     }

14.  }

a) test a is this
b) compile time error
c) tset a si siht
d) run time error

Answer: c

Explanation: Reversal of string using pointers.
Output:tset a si siht

10. What will be the output of given code snippet?

1.  class UnsafeCode

2.  {

3.      unsafe static void Main()

4.      {

5.          int* p ;

6.          int ch = 13*5;

7.          p = &(ch);

8.          Console.WriteLine(Convert.ToChar(*p));

9.          if (*p == 'A')

10.          Console.WriteLine(Convert.ToBoolean(1));

11.          else

12.          Console.WriteLine(Convert.ToBoolean(0));

13.          Console.ReadLine();

14.      }

15.  }

a) 65 False
b) 65 1
c) A True
d) A 1

Answer: c

Explanation: Convert.Tochar(*p) = A
Convert.ToBoolean(1) = True
Output: A
True