Chapter 4 - Loops

Question 1

What are the 3 kinds of loops?

Answer 1

while, do-while, and for loops

Question 2

What is the loop body?

Answer 2

The loop body is the statements inside the loop that are executed every iteration

Question 3

What is the difference between a while loop and a do-while loop?

Answer 3

A while loop checks the loop-continuation-condition before entering the loop body, while a do-while loop checks it after the first iteration

Question 4

When are while and do-while loops generally used?

Answer 4

When the number of iterations is not predetermined

Question 5

When is a for loop generally used?

Answer 5

When the loop body needs to be executed a certain number of times

Question 6

What is the syntax of the while loop?

Answer 6

while (loop-continuation-condition) {
Statement(s);
}

Question 7

What is the syntax of the do-while loop?

Answer 7

do {
Statement(s);
} while (loop-continuation-condition)

Question 8

What is the syntax of the for loop?

Answer 8

for (initial-action; loop-continuation-condition; action-after-each-iteration) {
Statement(s);
}

Question 9

Analyze the following statement:

double sum = 0;
for (double d = 0; d

Answer 9

D. The program compiles and runs fine.

Question 10

Which of the following loops correctly computes 1/2 + 2/3 + 3/4 + … + 99/100?

A:
double sum = 0;
for (int i = 1; i

Answer 10

E. CD

Question 11

The following loop displays _____.

for (int i = 1; i );
i++;
}

A. 1 2 3 4 5 6 7 8 9
B. 1 2 3 4 5 6 7 8 9 10
C. 1 2 3 4 5
D. 1 3 5 7 9
E. 2 4 6 8 10

Answer 11

D. 1 3 5 7 9

Question 12

Do the following two statements in (I) and (II) result in the same value in sum?

(I):
for (int i = 0; i<10; i++) {
sum += i;
}

Answer 12

Yes

Question 13

What is i after the following for loop?

int y = 0;
for (int i = 0; i<10; ++i) {
y += i;
}

A. 9
B. 10
C. 11
D. undefined

Answer 13

D. undefined

Explanation: The scope of i is inside the loop. After the loop, i is not defined.

Question 14

Given the following four patterns,

Pattern A
1
1  2
1  2  3
1  2  3  4
1  2  3  4  5
1  2  3  4  5  6

Pattern B 
1  2  3  4  5  6
1  2  3  4  5
1  2  3  4
1  2  3
1  2
1

Pattern C 
              1
           2 1
        3 2 1
     4 3 2 1
  5 4 3 2 1
6 5 4 3 2 1 

Pattern D
1 2 3 4 5 6
   1 2 3 4 5 
      1 2 3 4
         1 2 3
            1 2 
               1

Which of the pattern is produced by the following code?
    for (int i = 1; i = 1; j--)
        System.out.print(j );
      System.out.println();
    }

Answer 14

C

Question 15

Analyze the following fragment:

double sum = 0;
double d = 0;
while (d != 10.0) {
  d += 0.1;
  sum += sum + d;
}

A. The program does not compile because sum and d are declared double, but assigned with integer value 0.
B. The program never stops because d is always 0.1 inside the loop.
C. The program may not stop because of the phenomenon referred to as numerical inaccuracy for operating with floating-point numbers.
D. After the loop, sum is 0 + 0.1 + 0.2 + 0.3 + … + 1.9

Answer 15

C. The program may not stop because of the phenomenon referred to as numerical inaccuracy for operating with floating-point numbers.

Question 16

Analyze the following code:

public class Test {  
  public static void main (String args[]) {
    int i = 0;
    for (i = 0; i

Answer 16

C and D are correct.
Explanation: This is a logic error. System.out.println(i + 4) is not a part the for loop because the for loop ends with the last semicolon at for (i=0; i

Question 17

What will be displayed after the following loop terminates?

int number = 25;
int i;

boolean isPrime = true;
for (i = 2; i

Answer 17

D. i is 6 isPrime is false