C# Questions & Answers on While Loop Statements for Freshers

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

1.  static void Main(string[] args)

2.  {

3.      int i, j;

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

5.      {

6.          j = 1;

7.          while (i % j == 2)

8.          {

9.              j++;

10.          }

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

12.      }

13.      Console.ReadLine();

14.  }

a) 11 21 31
b) 1 12 13 1
c) 11 21 31
d) 1 1 2 1 3 1

Answer: c

Explanation: Since, condition never satisfied for any value of i and j for which (i % j == 2).Hence, j is always constant ‘1’ and ‘i’ increments for i = 1, 2, 3.
Output: 11 21 31.

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

1.  static void Main(string[] args)

2.  {

3.      float s = 0.1f;

4.      while (s <= 0.5f)

5.      {

6.          ++s;

7.          Console.WriteLine(s);

8.      }

9.      Console.ReadLine();

10.  }

a) 0.1
b) 1.1
c) 0.1 0.2 0.3 0.4 0.5
d) No output

Answer: b

Explanation: For the first while condition check when s = 0. If it is true as control goes inside loop ++s increments value of s by 1 as 1+0.1 = 1.1. So, for next condition while loop fails and hence, prints final value of s as 1.1.
Output: 1.1

3. Select the output for the following set of Code:

1.  static void Main(string[] args)

2.  {

3.      int i;

4.      i = 0;

5.      while (i++ < 5)

6.      {

7.          Console.WriteLine(i);

8.      }

9.      Console.WriteLine("\n");

10.      i = 0;

11.      while ( ++i < 5)

12.     {

13.         Console.WriteLine(i);

14.     }

15.     Console.ReadLine();

16. }

a) 1 2 3 4
1 2 3 4 5
b) 1 2 3
1 2 3 4
c) 1 2 3 4 5
1 2 3 4
d) 1 2 3 4 5
1 2 3 4 5

Answer: c

Explanation: For while(i++ < 5) current value of ‘i’ is checked first and hence prints incremented value afterwards.So, i =1, 2, 3, 4, 5.But, for while(++i < 5) current value is incremented first and then checks that value with given condition and hence then prints that value.So, i = 1, 2, 3, 4.
Output: 1 2 3 4 5
1 2 3 4

4. Select the output for the following set of Code:

1.  static void Main(string[] args)

2.  {

3.      int x = 0;  

4.      while (x < 20)

5.      {

6.          while (x < 10)

7.          {

8.              if (x % 2 == 0)

9.              {

10.                  Console.WriteLine(x);

11.              }

12.              x++;

13.          }

14.      }

15.      Console.ReadLine();

16.  }

a) 1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
b) 0 2 4 6 8 10 12 14 16 18 20
c) 0 2 4 6 8
d) 0 2 4 6 8 10

Answer: c

Explanation: Inner while loop condition checks for even number between 0 an 10 and hence prints number between the given range.
Output: 0 2 4 6 8.

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

1.  static void Main(string[] args)

2.  {

3.      int x;

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

5.      int c = 1;

6.      while (c <= x)

7.      {

8.          if (c % 2 == 0)

9.          {

10.              Console.WriteLine("Execute While " + c + "\t" + "time");

11.          }

12.          c++;

13.      }

14.      Console.ReadLine();

15.  }

16. for x = 8.

a) Execute while 1 time
Execute while 3 time
Execute while 5 time
Execute while 7 time
b) Execute while 2 time
Execute while 4 time
Execute while 6 time
Execute while 8 time
c) Execute while 1 time
Execute while 2 time
Execute while 3 time
Execute while 4 time
Execute while 5 time
Execute while 6 time
Execute while 7 time
d) Execute while 2 time
Execute while 3 time
Execute while 4 time
Execute while 5 time

Answer: b

Explanation: Checks condition if number is divisible by 2 then it will print it even number times as given for x = 8 so, prints between 2 to 8 times Similarly, for x = 5, Execute 2 and 4 time.
OUTPUT: Execute while 2 time.
Execute while 4 time.
Execute while 6 time.
Execute while 8 time.

6. Select the output for the following set of Code:

1.   static void Main(string[] args)

2.   {

3.       int n, r;

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

5.       while (n > 0)

6.       {

7.           r = n % 10;

8.           n = n / 10;

9.           Console.WriteLine(+r);

10.       }

11.       Console.ReadLine();

12.   }

13.  for n = 5432.

a) 3245
b) 2354
c) 2345
d) 5423

Answer: c

Explanation: Reverse of number using while loop.
Output: 2345.

7. Correct syntax for while statement is:

1.  a) while

2.     {

6.      }(condition);

7.  b) while(condition)

8.     {

11.      };

12.  c) while(condition)

13.     {

16.      }

17.  d) while(condition);

18.     {

21.      }

Answer:c

Explanation: By defination.

 
 

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

1.   static void Main(string[] args)

2.   {

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

4.       while (i  < 2.0f  &&  j  <= 2.0f)

5.       {

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

7.       }

8.       Console.ReadLine();

9.   }

a) 0.05f
b) 1.50f
c) -0.04999995f
d) 1.50f

Answer: c

Explanation: for while(i = 1.0f and j = 0.05f). We, had ‘&&’ condition which gives ‘1’. So, control enters while loop. Since, i = 1 and i++ = first execute then increment. So, first with ‘i’ value as 1.0f and ++j = first increment and then executes we had j = 1.05f and Since operation (i++ – ++j) gives us a negative sign number. So, we can stick our choice to option ‘c’ clearly. Now, as i = 2.0f so loop breaks.
Output:-0.04999995f.

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

1.  static void Main(string[] args)

2.  {

3.      int i = 0;

4.      while (i <= 50)

5.      {

6.          if (i % 10 == 0)

7.          continue;

8.          else

9.          break;

10.          i += 10;

11.          Console.WriteLine(i % 10);

12.     }

13. }

a) code prints output as 0 0 0 0 0
b) code prints output as 10 20 30 40 50
c) infinite loop but donot print anything
d) Code generate error

Answer: c

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

1.   static void Main(string[] args)

2.   {

3.       int i = 1, j = 1;

4.       while (++i <= 10)

5.       {

6.           j++;

7.       }

8.       Console.WriteLine(i+ "  " +j);

9.       Console.ReadLine();

10.   }

a) 12 11
b) 10 11
c) 11 10
d) 11 12

Answer: c

Explanation: As ++i, first increments then execute so, for ++i i is 11 and j++ is first execute then increments. So, j = 10.
Output:11 10.

11. Select the output for following set of Code :

1.    static void Main(string[] args)

2.    {

3.        int i = 1;

4.        while (i <= 1)

5.        {

6.            if ('A' < 'a')

7.            {

8.                Console.WriteLine("Hello...");

9.            }

10.            else

11.            {

12.               Console.WriteLine("Hi...");

13.            }

14.               i++;

15.        }

16.        Console.ReadLine();

17.    }

a) Hi…
b) Hello….
c) Hi…infinite times
d) Hello infinite times

Answer: b

Explanation: Ascii value of ‘A’ is 65 and ‘a’ is 97.So, clearly ‘A’ < ‘a’.
Output:Hello.

12. Select the output for the following set of codes:

1.   static void Main(string[] args)

2.   {

3.       int i = 0;

4.       while (i++ != 0) ;

5.       Console.WriteLine(i);

6.       Console.ReadLine();

7.   }

a) -127 to +127
b) 0 to 127
c) 1
d) Infinite loop condition

Answer: c

Explanation: i++ = first executes then increments as i = 0. So, i++ != 0, which is false clearly as i = 0. Now, control goes inside loop with i = 1. So, statement prints i = 1.
Output: 1.