C# Questions & Answers on Do While Loop Statements for Freshers

1. Select output for the following set of code :

1.  static void Main(string[] args)

2.  {

3.      int i = 1, j = 2, k = 3;

4.      do

5.      {

6.          Console.WriteLine((Convert.ToBoolean(Convert.ToInt32(i++))) && (Convert.ToBoolean(Convert.ToInt32(++j))));

7.      }while (i <= 3);

8.      Console.ReadLine();

9.  }

a) 0 0 0
b) True True True
c) 1 1 1
d) False False False

Answer: b

Explanation: 1 AND 1 = True.Similarly , non zero number || non zero number = True.
Output:True True True.

2. Select output for the following set of code :

1. static void Main(string[] args)

2. {

3.     float i = 1.0f, j = 0.05f;

4.     do

5.     {

6.         Console.WriteLine(i++ - ++j);

7.     }while (i < 2.0f && j <= 2.0f);

8.     Console.ReadLine();

9. }

a) 0.05
b) -0.05
c) 0.95
d) -0.04999995

Answer: d

Output : -0.04999995

3. Select the output for the following code :

1. static void Main(string[] args)

2. {

3.     int i = 1, j = 5;

4.     do

5.     {

6.         Console.WriteLine(i = i++ * j);

7.     }while (i <= 10);

8.     Console.ReadLine();

9. }

a) 5 10 15 20 25 30 35 40 45 50
b) 5 25
c) 5 11 16 21 26 31 36 41 46 51
d) 5 30

Answer: b

Explanation: For first step of loop i = 1 .So, i++ * j = 1 * 5 = 5 .For second step of loop i = 5 ,j = 5 .So, i++ * j = 25.As, i = 25 hence , 25 >=10 loop condition breaks.
Output: 5 25.

4. For the incomplete program below, which of the code fragment will not result in an infinite loop:

1.  static void Main(string[] args)

2.  {

3.      int i = 1234 ,j = 0;

4.       /*ADD CODE HERE */

5.      Console.WriteLine(j);

6.  }

a)

 do
    {
        j = j + (i % 10);
    }while ((i = i / 10)!= 0);

b)

do
    {
        j = j + (i % 10);
    }while ((i / 10)!= 0);

c)

do
    {
        j = j + (i % 10);
    }while ((i % 10)!= 0);

d)

do
    {
        j = j + (i % 10);
    }while ((i/10 == 0)!= 0);

Answer: a
Output :

static void Main(string[] args)
        {
              int i = 1234,j = 0;
              do
              {
                  j = j +( i % 10);
 
              }while ((i = i / 10)!= 0);
              Console.WriteLine(j);

}

 
 

5. Select the output for the following set of code :

1.  static void Main(string[] args)

2.  {

3.      long  x;

4.      x = Convert.ToInt32(Console.ReadLine());

5.      do

6.      {

7.          Console.WriteLine(x % 10);

8.      }while ((x = x / 10) != 0);

9.      Console.ReadLine();

10.  }

11.  enter x = 1234.

a) number of digits present in x
b) prints ‘1’
c) prints reverse of x
d) prints sum of digits of ‘x’

Answer: c

Explanation: Reverse of digits using while loop statements.
Output: 4321.

6. Select output for the following set of code :

1.  static void Main(string[] args)

2.  {

3.      int i, s = 0, a = 1, d;

4.      i = Convert.ToInt32(Console.ReadLine());

5.      do

6.      {

7.          d = i % (2 * 4);

8.          s = s + d * a;

9.      }while ((Convert.ToInt32(i = i / (2 * 4))) != 0 && (Convert.ToBoolean(Convert.ToInt32((a) = (a * 10)))));

10.      Console.WriteLine(s);

11.      Console.ReadLine();

12.  }

13. enter i = 342.

a) It finds binary equivalent of i
b) It finds octal equivalent of i
c) It finds sum of digits of i
d) It finds reverse of i

Answer: b

Explanation: None.
Output : i = 342.
s = 526.

7. Correct syntax for do while loop is :

a) do;
   {
    statement;
   }while (condition);
b) do(condition)
   {
     statement;
   }while;
c) do
   {
     statement;
   }while (condition)
d) do
   {
        statement;
   }while (condition);

Answer: d

Explanation: By definition
Output:do
{
statement;
}while (condition);

 
 

8. Select the output for the following set of code :

1. static void Main(string[] args)

2. {

3.     int x = 10;

4.     do

5.     {

6.         Console.WriteLine( x++);

7.     }

8.     while(Convert.ToBoolean(5) && Convert.ToBoolean(4) && Convert.ToBoolean(3) && Convert.ToBoolean(2) && Convert.ToBoolean(1) && Convert.ToBoolean(0));    

9.     Console.ReadLine();

10. }

a) 13
b) 15
c) 11
d) 10

Answer: d

Explanation: Here in do while condition ‘&&’ i.e ‘AND’operator return ‘0’ i.e false.So, as condition is false so program comes out of the loop.
Output : 10.

9. Select output for the following set of code :

1. static void Main(string[] args)

2. {

3.     int x;

4.     for (x = 10; x <= 15; x++)

5.     while (Convert.ToBoolean(Convert.ToInt32(x)))

6.     {

7.         do

8.         {

9.             Console.WriteLine(1);

10.             if (Convert.ToBoolean(x >> 1))

11.             continue;

12.         }while (Convert.ToBoolean(0));

13.         break;

14.     }

15.     Console.ReadLine();

16. }

a) 0 0 0….infinite times
b) 1 1 1….infinite times
c) 1 1 1 1 1 1
d) System outofflow exception error

Answer: c

Explanation: The execution of for loop is done for six consecutive times.
Output : 1 1 1 1 1 1

10. Select the output for the following set of code :

1. static void Main(string[] args)

2. {

3.     int x = 0;

4.     do

5.     {

6.         x++;

7.         if (x == 5)

8.         {

9.             x++;

10.             continue;

11.             break;

12.         }

13.         Console.WriteLine(x + " ");

14.     }

15. }while (x < 10);

a) 1 2 3 4 5
b) 10
c) 5 6 7 8 9 10
d) 1 2 3 4 5 6 7 8 9 10

Answer: d

Explanation: The condition will print the numbers from 1 to 10 when x == 5 and when x does not satisfy if condition until x < 10.
Output: 1 2 3 4 5 6 7 8 9 10 .

11. Select the output for the following set of code :

1. static void Main(string[] args)

2. {

3.     int x;

4.     for (x = 1; x <= 3; x++)

5.     {

6.         int j = 1;

7.         do

8.         {

9.             j++;

10.         }while (x % j == 2);

11.         Console.WriteLine(x + " " + j);

12.     }

13.     Console.ReadLine();

14. }

a) 1 12 1 3 1
b) 1 12 13 1
c) 12 22 32
d) 11 21 31

Answer: c

Output : 12 22 32.