a.
8
b.
9
c.
10
d.
11
e.
0
a.
8
b.
9
c.
10
d.
11
e.
0
Chapter 5 Loops
Section 5.2 The while Loop
1. How many times will the following code print “Welcome to Java”?
int count = 0;
while (count < 10) {
System.out.println(“Welcome to Java”);
count++;
}
#
2. Analyze the following code.
int count = 0;
while (count < 100) {
// Point A
System.out.println(“Welcome to Java!”);
count++;
// Point B
}
// Point C
a. count < 100 is always true at Point A
b. count < 100 is always true at Point B
c. count < 100 is always false at Point B
d. count < 100 is always true at Point C
e. count < 100 is always false at Point C
#
Section 5.3 Case Study: Guessing Numbers
3. How many times will the following code print “Welcome to Java”?
int count = 0;
while (count++ < 10) {
System.out.println(“Welcome to Java”);
}
a.
6 3 0
b.
6 3
c.
3 0
d.
3 0 –3
e.
0 –3
a.
8
b.
9
c.
10
d.
11
e.
0
to check if count < 10. So, the loop is executed 10 times for count from 0 to 9. The correct answer is C.
#
4. What is the output of the following code?
int x = 0;
while (x < 4) {
x = x + 1;
}
System.out.println(“x is ” + x);
a. x is 0
b. x is 1
c. x is 2
d. x is 3
e. x is 4
#
Section 5.5 Controlling a Loop with User Confirmation or a Sentinel Value
5. What will be displayed when the following code is executed?
int number = 6;
while (number > 0) {
number –= 3;
System.out.print(number + ” “);
}
#
Section 5.6 The do-while Loop
6. How many times will the following code print “Welcome to Java”?
int count = 0;
do {
System.out.println(“Welcome to Java”);
count++;
} while (count < 10);
a.
8
b.
9
c.
10
d.
11
e.
0
a.
8
b.
9
c.
10
d.
11
e.
0
a.
8
b.
9
c.
10
d.
11
e.
0
#
7. How many times will the following code print “Welcome to Java”?
int count = 0;
do {
System.out.println(“Welcome to Java”);
} while (count++ < 10);
#
8. How many times will the following code print “Welcome to Java”?
int count = 0;
do {
System.out.println(“Welcome to Java”);
} while (++count < 10);
#
9. What is the value in count after the following loop is executed?
int count = 0;
do {
System.out.println(“Welcome to Java”);
} while (count++ < 9);
System.out.println(count);
#
Section 5.7 The for Loop
10. Analyze the following statement:
double sum = 0;
for (double d = 0; d < 10;) {
d += 0.1;
sum += sum + d;
}
a. The program has a compile error because the adjustment is missing in the for loop.
b. The program has a compile error because the control variable in the for loop cannot be of the double type.
c. The program runs in an infinite loop because d < 10 would always be true.
d. The program compiles and runs fine.
#
11. Which of the following loops prints “Welcome to Java” 10 times?
A:
for (int count = 1; count <= 10; count++) {
System.out.println(“Welcome to Java”);
}
B:
for (int count = 0; count < 10; count++) {
System.out.println(“Welcome to Java”);
}
C:
for (int count = 1; count < 10; count++) {
System.out.println(“Welcome to Java”);
}
D:
for (int count = 0; count <= 10; count++) {
System.out.println(“Welcome to Java”);
}
a. BD
b. ABC
c. AC
d. BC
e. AB
#
12. Which of the following loops correctly computes 1/2 + 2/3 + 3/4 + … + 99/100?
A:
double sum = 0;
for (int i = 1; i <= 99; i++) {
sum = i / (i + 1);
}
System.out.println(“Sum is ” + sum);
B:
double sum = 0;
for (int i = 1; i < 99; i++) {
sum += i / (i + 1);
}
System.out.println(“Sum is ” + sum);
C:
double sum = 0;
for (int i = 1; i <= 99; i++) {
sum += 1.0 * i / (i + 1);
}
System.out.println(“Sum is ” + sum);
D:
double sum = 0;
for (int i = 1; i <= 99; i++) {
sum += i / (i + 1.0);
}
System.out.println(“Sum is ” + sum);
E:
double sum = 0;
for (int i = 1; i < 99; i++) {
sum += i / (i + 1.0);
}
System.out.println(“Sum is ” + sum);
a. BCD
b. ABCD
c. B
d. CDE
e. CD
#
13. The following loop displays .
for (int i = 1; i <= 10; i++) {
System.out.print(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
#
14. 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;
}
(II):
for (int i = 0; i < 10; i++) {
sum += i;
}
a. Yes
b. No
#
15. What is the output for y?
int y = 0;
for (int i = 0; i < 10; ++i) {
y += i;
}
System.out.println(y);
a.
10
b.
11
c.
12
d.
13
e.
45
#
16. 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
#
17. Is the following loop correct?
for ( ; ; );
a. Yes
b. No
Key:a Yes. This is equivalent to for (; true; ).
#
Section 5.8 Which Loop to Use?
18. 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
#
19. Analyze the following code:
public class Test {
public static void main (String[] args) {
int i = 0;
for (i = 0; i < 10; i++);
System.out.println(i + 4);
}
}
a. The program has a compile error because of the semicolon (;) on the for loop line.
b. The program compiles despite the semicolon (;) on the for loop line, and displays 4.
c. The program compiles despite the semicolon (;) on the for loop line, and displays 14.
d. The for loop in this program is same as for (i = 0; i < 10; i++) { }; System.out.println(i + 4);
#
Section 5.9 Nested Loops
20. How many times is the println statement executed?
for (int i = 0; i < 10; i++)
for (int j = 0; j < i; j++)
System.out.println(i * j)
a. 100
b. 20
c. 10
d. 45
#
21. Which pattern is produced by the following code?
for (int i = 1; i <= 6; i++) {
for (int j = 6; j >= 1; j—)
System.out.print(j <= i ? j + ” ” : ” ” + ” “);
System.out.println();
}
Pattern A
Pattern B
Pattern
C Pattern D
1
1 2 3 4 5 6
1
1 2 3 4 5 6
1 2
1 2 3 4 5
2 1
1 2 3 4 5
1 2 3
1 2 3 4
3 2 1
1 2 3 4
1 2 3 4
1 2 3
4 3 2 1
1 2 3
1 2 3 4 5
1 2
5 4 3 2 1
1 2
1 2 3 4 5 6
1
6 5 4 3 2 1
1
a. Pattern A
b. Pattern B
c. Pattern C
d. Pattern D
#
22. How many times is the println statement executed?
for (int i = 0; i < 10; i++)
for (int j = 0; j < 10; j++)
System.out.println(i * j);
a. 100
b. 20
c. 10
d. 45
#
Section 5.10 Minimizing Numerical Errors
23. To add 0.01 + 0.02 + … + 1.00, what order should you use to add the numbers to get better accuracy?
a. add 0.01, 0.02, …, 1.00 in this order to a sum variable whose initial value is 0.
b. add 1.00, 0.99, 0.98, …, 0.02, 0.01 in this order to a sum variable whose initial value is 0.
#
24. Analyze the following code.
double sum = 0;
for (double d = 0; d < 10; sum += sum + d) {
d += 0.1;
}
A.
9
B.
10
C.
11
D.
12
A. The program has a syntax error because the adjustment statement is incorrect in the for loop.
B. The program has a syntax error because the control variable in the for loop cannot be of the double type.
C. The program compiles but does not stop because d would always be less than 10.
D. The program compiles and runs fine.
#
Section 5.11 Case Studies
25. What is y after the following for loop statement is executed?
int y = 0;
for (int i = 0; i < 10; ++i) {
y += 1;
}
#
Section 5.12 Keywords break and continue
26. Will the following program terminate?
int balance = 10;
while (true) {
if (balance < 9)
break;
balance = balance – 9;
}
a. Yes
b. No
#
27. What is sum after the following loop terminates?
int sum = 0;
int item = 0;
do {
item++;
sum += item;
if (sum > 4)
break;
}
while (item < 5);
a. 5
b.
6
c.
7
d.
8
e.
9
#
28. What is the output after the following loop terminates?
int number = 25;
int i;
boolean isPrime = true;
for (i = 2; i < number && isPrime; i++) {
if (number % i == 0) {
isPrime = false;
}
}
System.out.println(“i is ” + i + ” isPrime is ” + isPrime);
a. i is 5 isPrime is true
b. i is 5 isPrime is false
c. i is 6 isPrime is true
d. i is 6 isPrime is false
#
29. What is the output after the following loop terminates?
int number = 25;
int i;
boolean isPrime = true;
for (i = 2; i < number; i++) {
if (number % i == 0) {
isPrime = false;
break;
}
}
System.out.println(“i is ” + i + ” isPrime is ” + isPrime);
a. i is 5 isPrime is true
b. i is 5 isPrime is false
c. i is 6 isPrime is true
a.
6
b.
7
c.
8
d.
9
e.
10
d. i is 6 isPrime is false
#
30. What is sum after the following loop terminates?
int sum = 0;
int item = 0;
do {
item++;
if (sum >= 4)
continue;
sum += item;
}
while (item < 5);
#
31. Will the following program terminate?
int balance = 10;
while (true) {
if (balance < 9)
continue;
balance = balance – 9;
}
a. Yes
b. No
#
32. What balance after the following code is executed?
int balance = 10;
while (balance >= 1) {
if (balance < 9)
continue;
balance = balance – 9;
A.
–1
B.
0
C.
1
D.
2
}
A.
–1
B.
0
C.
1
D.
2
E.
The loop does not end
#
33. What is the value of balance after the following code is executed?
int balance = 10;
while (balance >= 1) {
if (balance < 9)
break;
balance = balance – 9;
}
#
Section 5.13 Case Study: Checking Palindromes
34. What is the number of iterations in the following loop?
for (int i = 1; i < n; i++) {
// iteration
}
a. 2*n
b. n
c. n – 1
d. n + 1
#
35. What is the number of iterations in the following loop?
for (int i = 1; i <= n; i++) {
// iteration
}
a. 2*n
b. n
c. n – 1
d. n + 1
Key:b The loop is executed n times for i from 1 to n. So, the correct answer is B.
#
Section 5.14 Case Study: Displaying Prime Numbers
36. Suppose the input for number is 9. What is the output from running the following program?
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print(“Enter an integer: “);
int number = input.nextInt();
int i;
boolean isPrime = true;
for (i = 2; i < number && isPrime; i++) {
if (number % i == 0) {
isPrime = false;
}
}
System.out.println(“i is ” + i);
if (isPrime)
System.out.println(number + ” is prime”);
else
System.out.println(number + ” is not prime”);
}
}
a. i is 3 followed by 9 is prime
b. i is 3 followed by 9 is not prime
c. i is 4 followed by 9 is prime
d. i is 4 followed by 9 is not prime
#
37. Analyze the following code:
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
int sum = 0;
for (int i = 0; i < 100000; i++) {
Scanner input = new Scanner(System.in);
sum += input.nextInt();
}
}
}
a. The program does not compile because the Scanner input = new Scanner(System.in); statement is inside the loop.
b. The program compiles, but does not run because the Scanner input = new Scanner(System.in); statement is inside
the loop.
c. The program compiles and runs, but it is not efficient and unnecessary to execute the Scanner input = new
Scanner(System.in); statement inside the loop. You should move the statement before the loop.
d. The program compiles, but does not run because there is not prompting message for entering the input.