Q: Question 2How are these statements different from each other?i. breakii. continueiii. System.exit(0)iv. return

(i) The break statement terminates the current loop or switch statement. The execution then continues from the statement immediately following the current loop or switch statement.(ii) The continue statement tells the computer to skip the rest of the current iteration of the loop. However, instead of jumping out of the loop completely like break statement, it jumps back to the beginning of the loop and continues with the next iteration. This includes the evaluation of the loop controlling condition to check whether any further iterations are required.(iii) Unlike break and continue statements which are used to control the flow of execution, System.exit(0) command terminates the execution of the program by stopping the Java Virtual Machine which is executing the program. It is generally used when due to some reason it is not possible to continue with the execution of the program.(iv) A return statement is used to end the execution of a method and return a value to the calling method, optionally.

Q: Question 5Convert the following for loop statement into the corresponding while loop and do-while loop:int sum = 0; for (int i = 0; i <= 50; i++) sum = sum + i;

while loopint sum = 0, i = 0; while (i <= 50) { sum = sum + i; i++; }do-while loopint sum = 0, i = 0; do { sum = sum + i; i++; } while(i <= 50);

Q: Question 6What are the differences between while loop and do-while loop?

do-while loopwhile loopdo-while is an exit-controlled loop.while is an entry-controlled loop.do-while loop checks the test condition at the end of the loop.while loop checks the test condition at the beginning of the loop.do-while loop executes at least once, even if the test condition is false.while loop executes only if the test condition is true.do-while loop is suitable when we need to display a menu to the user.while loop is helpful in situations where number of iterations is not known.

Q: Question 7(i)How many times are the following loop bodies repeated? What is the final output in each case?int x = 2; while (x < 20) if (x % 2 == 0) System.out.println(x);

The loop repeats for infinite times.Output2 2 2 2 2 . . . . ExplanationThe value of x is 2. The test condition of while loop — x < 20 is true and the test condition of if — x % 2 == 0 is also true. So the loop prints the value of x i.e., 2 for the first time.In the absence of update expression, the while loop continues infinitely and keeps on printing 2 on the output screen.

Q: Question 7(ii)How many times are the following loop bodies repeated? What is the final output in each case?int y = 2; while (y < 20) if (y % 2 == 0) System.out.println(y++);

The loop repeats for infinite times.Output2 ExplanationThe value of y is 2. The test condition of while loop — y < 20 is true and the test condition of if — y % 2 == 0 is also true. So the loop prints the value of y i.e., 2 for the first time and then the postfix operator increments it to 3.In the next iteration, the test condition y < 20 is true but the condition of if — y % 2 == 0 is false. Thus, there is no updation in the value of y and y remains less than 20. This creates an infinite loop.

Question 1

Question 1What are loop control structures? What are the essential segments of a loop control structure?

Accepted Answer

A loop is a set of instructions that is continually repeated until a certain condition is met. Looping control structures refer to certain looping constructs which execute a block of code repeatedly until a certain condition remains true. For example, for loop, while loop, do - while loop etc.The essential parts of a looping control structure are as follows:Initialisation — This segment initialises the loop control variable before starting the loop. It is executed only once at the beginning of the loop.For example, int counter = 1;Test-condition — The test-condition is the expression that is evaluated at the beginning of each iteration. Its value determines whether the body of the loop is to be executed (test condition is true) or the loop is to be terminated (test condition is false).For example, counter <= 10Update — This is the increment or decrement operation of the control variable. This operation is performed at the end of each iteration.For example, counter++;

Question 2

Question 2How are these statements different from each other?i. breakii. continueiii. System.exit(0)iv. return

Accepted Answer

(i) The break statement terminates the current loop or switch statement. The execution then continues from the statement immediately following the current loop or switch statement.(ii) The continue statement tells the computer to skip the rest of the current iteration of the loop. However, instead of jumping out of the loop completely like break statement, it jumps back to the beginning of the loop and continues with the next iteration. This includes the evaluation of the loop controlling condition to check whether any further iterations are required.(iii) Unlike break and continue statements which are used to control the flow of execution, System.exit(0) command terminates the execution of the program by stopping the Java Virtual Machine which is executing the program. It is generally used when due to some reason it is not possible to continue with the execution of the program.(iv) A return statement is used to end the execution of a method and return a value to the calling method, optionally.

Question 3

Question 3(i)Identify all the errors in the following statements.for (int i = 5; i > 0; i++)
{
    System.out.println("Java is fun!");
}

Accepted Answer

The test expression i > 0 will always remain true and hence, the for loop will become an infinite loop and keep on iterating.

Question 4

Question 3(ii)Identify all the errors in the following statements.while (x < 1 && x > 50)
{
    a = b;
}

Accepted Answer

The test expression x < 1 && x > 50 will never be true as the conditions x < 1 and x > 50 cannot be true at the same time. Thus, the && operator will always result in false.

Question 5

Question 3(iii)Identify all the errors in the following statements.while (x ==	y)
{
    xx = yy;
    x = y;
}

Accepted Answer

The test expression x == y will always remain true as in each iteration x = y is executed, which will store the value of y in x. Thus, an infinite loop will be generated.

Question 6

Question 4What is an empty statement? Explain its usefulness.

Accepted Answer

Empty statement consists only of a semicolon ;. It is useful when we want to make a loop an empty loop.To make a for loop an empty loop, we write the following code:for (int i = 1 ; i <=10 ; i ++);

Question 7

Question 5Convert the following for loop statement into the corresponding while loop and do-while loop:int sum = 0;
for (int i = 0; i <= 50; i++)
    sum = sum + i;

Accepted Answer

while loopint sum = 0, i = 0;
while (i <= 50)    {
    sum = sum + i;
    i++;
}do-while loopint sum = 0, i = 0;
do {
    sum = sum + i;
    i++;
} while(i <= 50);

Question 8

Question 6What are the differences between while loop and do-while loop?

Accepted Answer

do-while loopwhile loopdo-while is an exit-controlled loop.while is an entry-controlled loop.do-while loop checks the test condition at the end of the loop.while loop checks the test condition at the beginning of the loop.do-while loop executes at least once, even if the test condition is false.while loop executes only if the test condition is true.do-while loop is suitable when we need to display a menu to the user.while loop is helpful in situations where number of iterations is not known.

Question 9

Question 7(i)How many times are the following loop bodies repeated? What is the final output in each case?int x = 2;
while (x < 20)
    if (x % 2 == 0)
        System.out.println(x);

Accepted Answer

The loop repeats for infinite times.Output2
2
2
2
2
.
.
.
.
ExplanationThe value of x is 2. The test condition of while loop — x < 20 is true and the test condition of if — x % 2 == 0 is also true. So the loop prints the value of x i.e., 2 for the first time.In the absence of update expression, the while loop continues infinitely and keeps on printing 2 on the output screen.

Question 10

Question 7(ii)How many times are the following loop bodies repeated? What is the final output in each case?int y = 2;
while (y < 20)
    if (y % 2 == 0) 
        System.out.println(y++);

Accepted Answer

The loop repeats for infinite times.Output2
ExplanationThe value of y is 2. The test condition of while loop — y < 20 is true and the test condition of if — y % 2 == 0 is also true. So the loop prints the value of y i.e., 2 for the first time and then the postfix operator increments it to 3.In the next iteration, the test condition y < 20 is true but the condition of if — y % 2 == 0 is false. Thus, there is no updation in the value of y and y remains less than 20. This creates an infinite loop.

Question 11

Question 7(iii)How many times are the following loop bodies repeated? What is the final output in each case?int z = 2;
while (z < 20)
    if ((z++) % 2 == 0) 
        System.out.println(z);

Accepted Answer

The loop repeats for 18 times.Output3
5
7
9
11
13
15
17
19
ExplanationThe loop executes 18 times. Value of z is printed 9 times inside the loop. The condition if((z++) % 2 == 0) will be false when z is odd and true when z is even. Value of z will be incremented after if check is performed due to post increment operator z++. Execution of the loop is summarized in the table below:Iterationsz(z++) % 2 == 0OutputRemarks1st2True3Value of z becomes 3 after if check as z++ increments it after the evaluation of (z++) % 2 == 0. Hence, 3 is printed.2nd3Falsez becomes 4 after if check3rd4True5z becomes 5.4th5Falsez becomes 6.5th6True7z becomes 7.6th7Falsez becomes 8.7th8True9z becomes 9.8th9Falsez becomes 10.9th10True11z becomes 11.10th11Falsez becomes 12.11th12True13z becomes 13.12th13Falsez becomes 14.13th14True15z becomes 15.14th15Falsez becomes 16.15th16True17z becomes 17.16th17Falsez becomes 18.17th18True19z becomes 19.18th19Falsez becomes 20.As value of z is now 20, the test condition of while loop becomes false hence, 19th iteration of the loop is not executed.

Question 12

Question 9What is the output produced by the following code?int num = 20;
while (num > 0) 
{
    num = num - 2;
    if (num == 4)
        break ;
    System.out.println(num);
}
System.out.println("Finished");

Accepted Answer

Output18
16
14
12
10
8
6
Finished
ExplanationThe initial value of num is 20. Every time the while loop is executed, num decreases by 2. Execution of the loop is summarized in the table below:IterationnumTest Conditionnum > 0OutputRemarks1st20True18num becomes 18 (20 - 2)if condition false2nd18True16num becomes 16 (18 - 2)if condition false3rd16True14num becomes 14 (16 - 2)if condition false4th14True12num becomes 12 (14 - 2)if condition false5th12True10num becomes 10 (12 - 2)if condition false6th10True8num becomes 8 (10 - 2)if condition false7th8True6num becomes 6 (8 - 2)if condition false8th6Truenum becomes 4 (6 - 2)if condition becomes true, loop terminates.Since, in 8th iteration num becomes 4, the condition of if statement becomes true. break statement is executed and control jumps out of while loop to the println statement and "Finished" is printed on the screen.

Question 13

Question 10What is the output produced by the following code?int num = 10;
while (num > 0)
{
    num = num - 2;
    if (num == 2)
        continue;   
    System.out.println(num);
}
System.out.println("Finished");

Accepted Answer

Output8
6
4
0
Finished
ExplanationThe initial value of num is 10. Every time the while loop is executed, num decreases by 2. Execution of the loop is summarized in the table below:IterationnumTest Conditionnum > 0OutputRemarks1st10True8num becomes 8 (10 - 2)if condition false2nd8True6num becomes 6 (8 - 2)if condition false3rd6True4num becomes 4 (6 - 2)if condition false4th4Truenum becomes 2 (4 - 2)if condition becomes true, Continue statement sends control to next iteration of while loop5th2True0num becomes 0 (2 - 0)if condition falseAfter 5th iteration, num becomes 0 so the loop terminates.Since, the body of if contains continue statement, when num becomes 2, control ignores the remaining statements in the loop and starts the next iteration of the loop.

Question 14

Question 11Write a program to input n number of integers and find out:i. Number of positive integersii. Number of negative integersiii. Sum of positive numbersiv. Product of negative numbersv. Average of positive numbersimport java.util.Scanner;

public class KboatIntegers
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        int pSum = 0, pCount = 0, nPro = 1, nCount = 0;
        System.out.println("Enter n:");
        int n = in.nextInt();
        
        System.out.println("Enter " + n + " integers:");
        for (int i = 1; i <= n; i++) {
            int num = in.nextInt();
            if (num >= 0) {
                pSum += num;
                pCount++;
            }
            else {
                nPro *= num;
                nCount++;
            }
        }
        
        double pAvg = pSum/(double)pCount;
        System.out.println("Positive Integers = " + pCount);
        System.out.println("Negative Integers = " + nCount);
        System.out.println("Sum of Positive = " + pSum);
        System.out.println("Product of Negative = " + nPro);
        System.out.println("Average of Positive = " + pAvg); 
        
    }
}Output

Accepted Answer