Question

Look at the following program:

int main( )

{int exponent = 1;

int three = 1;

while (exponent <= 5)

{ three = three * 3;

cout << two << endl;

++exponent; }

return 0; }

(a) What is displayed?

(b) Change the while loop (and body of the loop) to a for loop.

Answer 1

int main()

{

                int exponent = 1;

                int three = 1;

                while (exponent <= 5)

                {

                                three = three * 3;

                                cout << three << endl;

                                ++exponent;

                }

                return 0;

}

(a) What is displayed?

Answer: The output of the above program is

3

9

27

81

243

Explanation: We have a variable three assigned with value 1.

Next we have have loop that runs from 1 to 5 each time multiply three by 3 and display it.

We have three = 1

Iteration 1: exponent = 1 (condition true)

                three = three * 3 => Now the value in three is 1 * 3 = 3, print it

Iteration 2: exponent = 2 (condition true)

                three = three * 3 => Now the value in three is 3 * 3 = 9, print it

Iteration 3: exponent = 3 (condition true)

                three = three * 3 => Now the value in three is 9 * 3 = 27, print it

Iteration 4: exponent = 4 (condition true)

                three = three * 3 => Now the value in three is 27 * 3 = 81, print it

Iteration 5: exponent = 5 (condition true)

                three = three * 3 => Now the value in three is 81 * 3 = 243, print it

Next exponent will be 6 and the loop terminates.

Hence the ouput is

3

9

27

81

243

Output of code using while loop

(b) Change the while loop (and body of the loop) to a for loop.

Answer:

int main()

{

                int exponent = 1;

                int three = 1;

                for(; exponent <= 5; exponent++)

                {

                                three = three * 3;

                                cout << three << endl;

                }

                return 0;

}

Output after modifying code to use for loop: