C# Questions & Answers on For Loop Statements for Freshers

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

1.  static void Main(string[] args)

2.  {

3.      int i;

4.      for (i = 0;  ; )

5.      {

6.          Console.WriteLine("hello");

7.      }

8.      Console.ReadLine();

9.  }

a) No output
b) hello
c) hello printed infinite times
d) Code will give error as expression syntax

Answer: c

Explanation: Testing condition for the loop is absent.So,loop will continue executing.
Output : hello
hello
hello
.
.
.

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

1.   static void Main(string[] args)

2.   {

3.       float f;

4.       for (f = 0.1f; f <= 0.5; f += 1)

5.       Console.WriteLine( ++f );

6.       Console.ReadLine();

7.   }

a) 1.1
b) 0.1
c) 0.1 0.2 0.3 0.4 0.5
d) None of the mentioned

Answer: a

Explanation: f =0.1 and ++f = 0.1+1 = 1.1.So,1.1>0.5,Condition fails and hence loop terminates.
Output : 1.1

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

1.  static void Main(string[] args)

2.  {

3.      int I, X;

4.      for (I = 1; I <= (9 % 2 + I); I++)

5.      {

6.          X = (I * 3 + I * 2) / I;

7.          Console.WriteLine(X);

8.      }

9.      Console.ReadLine();

10.  }

a) Output of code is 5 10
b) Output is 5 5 5 5
c) Print 5 infinite times
d) None of the mentioned

Answer: c

Explanation: Testing condition is always incremented i.e i never ‘>’ (9%2+I).So,loop will never terminate.
Output : 5 5 5…..

4. Select output for the following set of code:

1.  static void Main(string[] args)

2.  {

3.      int I, J = 0;

4.      for (I = 1; I < 10; ) ;

5.      {

6.          J = J + I;

7.          I += 2;

8.      }

9.      Console.WriteLine("Sum of first 10 even numbers is:"+J);

10.      Console.ReadLine();

11.  }

a) 1 2 3 4 5 6 7 8 9
b) 25
c) 1
d) Run time error

Answer: d

Explanation: Due to presence of ‘;’ after for()loop condition do not work as according to the statement.Remove the ‘;’.
Output : 25.

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

1.   static void Main(string[] args)

2.   {

3.       int i = 5;

4.       for (; Convert.ToBoolean(Convert.ToInt32(i)); Console.WriteLine(i--)) ;

5.       Console.ReadLine();

6.   }

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

Answer: c

Explanation: Since, i = 5 and test condition is executed until i!=0.So, i– decrements value of i till condition is satisfied.
Output: 5 4 3 2 1

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

1.  static void Main(string[] args)

2.  {

3.      int i, s = 0;

4.      for (i = 1; i <= 10; s = s + i, i++);

5.      {

6.          Console.WriteLine(s);

7.      }

8.      Console.ReadLine();

9.  }

a) Code report error
b) Code runs in infinite loop condition
c) Code gives output as 0 1 3 6 10 15 21 28 36 45
d) Code give output as 55

Answer: d

Explanation: Since occurrence of termination symbol(;) at end of for loop.
Output: 55.

7. Which statement is correct among the mentioned statements?

1. The for loop works faster than a while loop
2. for( ; ; )implements an infinite loop

a) Only 1 is correct
b) Only 2 is correct
c) Both 1 and 2 are correct
d) Both 1 and 2 are incorrect

Answer: b

Explanation: By defination.

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

1.   {

2.       int i;

3.       Console.WriteLine("Hi");

4.       for (i = 1; i <= 10; i++)

5.           Program.Main(args);

6.       Console.ReadLine();

7.   }

a) Prints ‘Hi’ for one time
b) Prints ‘Hi’ for infinite times
c) Stack overflow exception Condition generated
d) None of above mentioned

Answer: c

Explanation: Ocurrence of ‘main()’ condition after for loop.
Output: Hi
Hi
.
.
stack overflow exception.

9. Which of the code should be added to get the following output?

1.     * * * * *

2.     * * * *

3.     * * *

4.     * *

5.     *

6.    static void Main(string[] args)

7.    {

8.        int i,j;

9.      /* Add code here */

11.   }

a) for (i = 0;i <= 4; i++)
{
for(j = 0;j <= 4; j++)
console.WriteLine(“*”);
console.WriteLine(“\n”);
}
b) for (i = 0;i <= 4; i++)
{
for(j = 4;j <= i; j–)
console.WriteLine(“*”);
console.WriteLine(“\n”);
}

c) for (i = 0;i <= 4; i++)
{
for (j = i;j <= 4; j++)
console.WriteLine(“*”);
console.WriteLine(“\n”);
}

d) for ( i = 0;i <= 4; i++)
{
for (j = 0;j <= i; j++)
console.WriteLine(“*”);
console.WriteLine(“\n”);
}

Answer: c

Explanation: Input in Console and run the code.

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

1.    static void Main(string[] args)

2.    {

3.        int i;

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

5.        {

6.            switch (i)

7.            {

8.            case 0:

9.                Console.WriteLine("zero");

10.                break;

11.            }

12.            if (i > 0)

13.                Console.WriteLine("A");

14.            else if (i < 0)

15.                Console.WriteLine("B");

16.        }

17.        Console.ReadLine();

18.    }

a) B B zero A A A
b) B zero A A A
c) B B B zero A A A
d) A A A zero B B B

Answer: c

Explanation: for i =-3,-2,-1 statement executed as B.for i = 0,it is zero and for i =1,2,3 again statement printed as A seperately for each value of i.
Output: B B B zero A A A.

11. Which of the following is not infinite loop?

a) for( ;’0′; )
b) for( ;’0′; )
c) for( ;’1′; )
d) for( ;’1′; )

Answer: b

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

1.   static void Main(string[] args)

2.   {

3.       int i, j;

4.       for (i = 1, j = i; i <= 3 && j >= 0; i++, j--)

5.       {

6.           if (i == j)

7.               continue;

8.           else

9.               Console.WriteLine(j);

10.       }

11.       Console.ReadLine();

12.   }

a) i = 0, j = 1;
b) i = 1, j = 0;
c) j = 0;
d) None of the mentioned

Answer: c

Explanation: Since for i = 1, j = 1 and 1 <= 3 also 1 >= 0 we had i == j.But after i++ and j–. The initial value of ‘j’ which is ‘0’ as j– preferred other than value of ‘j’ in i = j.
Output:j = 0.

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

1.  static void Main(string[] args)

2.  {

3.      int i = -10;

4.      for ( ;Convert.ToBoolean(Convert.ToInt32(i)) ;Console.WriteLine(i++)) ;

5.      Console.ReadLine();

6.  }

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

Answer: c

Explanation: For first value of i = -10.Condition is executed until i!=0.
Output: -10 -9 -8 -7 -6 -5 -4 -3 -2 -1.