Deck 6: Loops

Question 1

The code snippet below checks whether a given number is a prime number. What will be the result of executing it? public static void main(String[] args)
{
Int j = 2;
Int result = 0;
Int number = 0;
Scanner reader = new Scanner(System.in);
System.out.println("Please enter a number: ");
Number = reader.nextInt();
While (j <= number / 2) // better is while (j * j <= number)
{
If (number % j == 0)
{
Result = 1;
}
J++;
}
If (result == 1)
{
System.out.println("Number: " + number + " is Not Prime.");
}
Else
{
System.out.println("Number: " + number + " is Prime. ");
}
}

A) The code snippet will not compile.
B) The code snippet will display the desired result.
C) The code snippet will display an incorrect result. // incorrect if number is 1
D) The code snippet will loop forever.

Answer 1

B

Question 2

What output does this while loop generate? j = 6;
While (j > 0)
{
System.out.print(j + ", ");
J--;
}

A) No output is generated.
B) 6, 5, 4, 3, 2, 1
C) 6, 5, 4, 3, 2, 1,
D) The output is infinite.

Answer 2

C

Question 3

How many times does the code snippet below display "Hello"?
Int i = 0;
While (i != 15)
{
System.out.println("Hello");
I++;
}

A) Infinite times
B) 14 times
C) 15 times
D) 16 times

Answer 3

C

Question 4

What is the output of the following code fragment?
Int i = 1;
Int sum = 0;
While (i <= 15)
{
Sum = sum + i;
I++;
}
System.out.println("The value of sum is " + sum);

A) The value of sum is 0
B) The value of sum is 105
C) The value of sum is 120
D) The value of sum is 136

Question 5

What is the output of the following code snippet?
Int i = 1;
While (i <= 10)
{
System.out.println("Inside the while loop");
I = i + 10;
}

A) No output because of compilation error.
B) "Inside the while loop" will be displayed 10 times.
C) No output after successful compilation.
D) "Inside the while loop" will be displayed only once.

Question 6

What is the output of the following code snippet?
Int i = 1;
While (i < 20)
{
System.out.print(i + " ");
I = i + 2;
If (i == 15)
{
I = 19;
}
}

A) 1 3 5 7 9 11 13 15 17 19
B) 1 3 5 7 9 11 13 19
C) 1 3 5 7 9 11 13 15 17
D) 1 3 5 7 9 11 13 17 19

Question 7

How many times does the following code fragment display "Hi"?
Int i = 10;
While (i >= 0)
{
System.out.println("Hi");
I--;
}

A) 9 times
B) 10 times
C) 11 times
D) 12 times

Question 8

What are the values of i and j after the following code fragment runs?
Int i = 60;
Int j = 50;
Int count = 0;
While (count < 5)
{
I = i + i;
I = i + 1;
J = j - 1;
J = j - j;
Count++;
}
System.out.println("i=" + i + ", j=" + j);

A) i = 1951, j = 0
B) i = 1951, j = 45
C) i = 65, j = 1
D) i = 65, j = 45

Question 9

How many times does the code snippet given below display "Loop Execution"?
Int i = 1;
While (i != 10)
{
System.out.println ("Loop Execution");
I++;
}

A) Infinite times
B) 8 times
C) 9 times
D) 10 times

Question 10

What is the output of the code snippet given below? String s = "abcde";
Int i = 1;
While (i < 5)
{
System.out.print);
I++;
}

A) No output
B) abcd
C) abcde
D) bcde

Question 11

What is the output of the code snippet given below?
Int i = 0;
While (i != 9)
{
System.out.println("" + i);
I = i + 2;
}

A) No output
B) 0 2 4 6 8
C) 10 12 14 16 18 …. (infinite loop)
D) 0 2 4 6 8 10 12 14 …. (infinite loop)

Question 12

What is the output of the code snippet given below? String s = "12345";
Int i = 1;
While (i < 5)
{
System.out.print);
I++;
}

A) No output
B) 1234
C) 12345
D) 2345

Question 13

What are the values of i and j after the following code snippet is run?
Int i = 10;
Int j = 20;
Int count = 0;
While (count < 5)
{
I = i + i;
I = i + 1;
J = j - 1;
J = j - j;
Count++;
}
System.out.println("i = " + i + ", j = " + j);

A) i = 45, j = 1
B) i = 351, j = 0
C) i = 351, j = 2
D) i = 1311, j = 35

Question 14

Which error type does the "off-by-one" error belong to?

A) Syntax error
B) Compile-time error
C) Run-time error
D) Infinite loop

Question 15

What is the output of the code fragment given below?
Int i = 0;
Int j = 0;
While (i < 125)
{
I = i + 2;
J++;
}
System.out.println(j);

A) 0
B) 62
C) 63
D) The code fragment displays no output because it does not compile.

Question 16

What is the output of the following code fragment?
Int i = 1;
Int sum = 0;
While (i <= 11)
{
Sum = sum + i;
I++;
}
System.out.println("The value of sum is " + sum);

A) The value of sum is 65
B) The value of sum is 66
C) The value of sum is 55
D) The value of sum is 56

Question 17

What is the output of the following code snippet?
Int i = 1;
While (i < 10)
{
System.out.print(i + " ");
I = i + 2;
If (i == 5)
{
I = 9;
}
}

A) 1 3 5
B) 1 3 9
C) 1 3 5 7 9
D) 1 3 5 9

Question 18

How many times will the following loop run?
Int i = 0;
While (i < 10)
{
System.out.println(i);
I++;
}

A) 0
B) 8
C) 9
D) 10

Question 19

What is the output of the following code snippet? double a = 2;
Int n = 16;
Double r = 1;
Double b = a;
Int i = n;
While (i > 0)
{
If (i % 2 == 0) // n is even
{
B = b * b;
I = i / 2;
}
Else
{
R = r * b;
I--;
}
}
System.out.println("r = " + r);

A) r = 16.0
B) r = 128.0
C) r = 4096.0
D) r = 65536.0

Question 20

What is the output of the code fragment given below?
Int i = 0;
Int j = 0;
While (i < 27)
{
I = i + 2;
J++;
}
System.out.println("j=" + j);

A) j=27
B) j=12
C) j=13
D) j=14

Question 21

What is the output of the code snippet given below?
Int i = 0;
While (i != 11)
{
System.out.print(" " + i);
I = i + 2;
}

A) No output
B) 0 2 4 6 8
C) 10 12 14 16 18 …. (infinite loop)
D) 0 2 4 6 8 10 12 14 …. (infinite loop)

Question 22

What will be the result of running the following code fragment?
Int year = 0;
Double rate = 5;
Double principal = 10000;
Double interest = 0;
While (year < 10)
{
Interest = (principal * year * rate) / 100;
System.out.println("Interest " + interest);
}

A) The code fragment will display the interest calculated for nine years.
B) The code fragment will continue to display the calculated interest forever because the loop will never end.
C) The code fragment will not display the calculated interest and halt abruptly.
D) The code fragment will not display any output because it will not compile.

Question 23

What are the values of i and j after the following code snippet executes?
Int i = 60;
Int j = 50;
Int count = 0;
While (count < 5)
{
I = i + i;
I = i + 1;
J = j - 1;
J = j - j;
Count++;
}
System.out.println(i);
System.out.println(j);

A) i = 65, j = 1
B) i = 65, j = 45
C) i = 1951, j = 0
D) i = 1951, j = 45

Question 24

Which of the following code snippets displays the output exactly 10 times?

A) int i = 0;
While (i < 10);
{
System.out.println("This is example 1.");
I++;
}
B) int i = 0;
While (i < 10)
{
System.out.println("This is example 2.");
I++;
}
C) int i = 0;
While (i < 10)
{
System.out.println("This is example 3.");
}
D) int i = 1;
While (i < 10)
{
System.out.println("This is example 4.");
I++;

Question 25

How many times does the following code snippet display "Loop Execution"? for (int i = 0; i < 10; i++);
{
System.out.println("Loop Execution");
}

A) Ten times.
B) The code snippet does not run because of a compile error.
C) Infinite loop.
D) Only one time.

Question 26

How many times does the loop execute in the following code fragment?
Int i;
For (i = 0; i < 50; i = i + 4)
{
System.out.println(i);
}

A) 11
B) 12
C) 13
D) 14

Question 27

What is the output of the code snippet given below?
Int i = 0;
While (i != 11)
{
System.out.print(i + " ");
I = i + 3;
}

A) No output
B) 0 3 6 9 12 15 18
C) 0 1 3 5 7 9
D) 0 3 6 9 …. (infinite loop)

Question 28

Select the statement that correctly completes the loop in this code snippet.
Int years = 20;
Double balance = 10000;
While (years > 0)
{
__________
Double interest = balance * rate / 100;
Balance = balance + interest;
}

A) years++;
B) years--;
C) balance++;
D) balance--;

Question 29

What is the output of the following code snippet?
Int i = 1;
While (i != 9)
{
System.out.print(i + " ");
I++;
If (i == 9)
{
System.out.println("End");
}
}

A) 1 End
B) 1 End (infinite loop)
C) 1 2 3 4 5 6 7 8 End
D) 1 2 3 4 5 6 7 8 End (infinite loop)

Question 30

Which of the following is considered a loop with a bound that could be problematic?

A) for (i = 1; i != n; i++)
B) for (years = n; years < 0; years--)
C) for (i = 1; i <= n; i++)
D) for (int i = 1; i <= 10; i++)

Question 31

What values does counter variable i assume when this loop executes? for (int i = 20; i >= 2; i = i - 6)
{
System.out.print(i + ",");
}

A) 20, 14, 8, 2
B) 20, 14, 8, 2, -4
C) 20, 14, 8
D) 14, 8, 2

Question 32

When hand-tracing a portion of code, which statement about Boolean conditions is true?

A) They typically are too complex to be evaluated.
B) They do not need to be monitored because their result usually is not stored in a variable.
C) It is rare to encounter a Boolean condition.
D) They are crucial to evaluate since they determine if-statement conditions and looping.

Question 33

What is the output of the code snippet given below?
Int i;
Int j = 0;
For (i = 0; i < 5; i++)
{
If (i % 2 == 0)
{
I = i + 2;
J++;
}
Else
{
I++;
J = j + 2;
}
J++;
}
System.out.println("i=" + i + ", j=" + j);

A) i=7, j =7
B) i =7, j =6
C) i =6, j =7
D) i =5, j =5

Question 34

What changes do you need to make in the following code snippet to display "Let us learn Java" exactly 10 times?
Int i = 0;
While (i <= 10)
{
System.out.println("Let us learn Java");
I++;
}

A) while (i < 9)
B) while (i < 11)
C) while (i < 12)
D) int i = 1;

Question 35

When hand tracing, drawing a line through the value stored in a variable means that

A) The value stored there has changed to something new
B) The variable is the wrong data type for the code being executed
C) The expression being evaluated uses that variable
D) The variable must be inside a loop

Question 36

What is the output of the following code snippet?
Int f1 = 0;
Int f2 = 1;
Int fRes;
System.out.print(f1 + " ");
System.out.print(f2 + " ");
For (int i = 1; i < 10; i++)
{
FRes = f1 + f2;
System.out.print(fRes + " ");
F1 = f2;
F2 = fRes;
}
System.out.println();

A) 0 1 5 7 9 11 13 15 17 19
B) 0 1 1 2 3 5 8 13 21 34 55
C) 0 1 4 6 8 10 12 14 16 18
D) 0 1 6 7 9 12 14 17 19 21

Question 37

The process of hand-tracing code is valuable because

A) It is usually faster than just running the code.
B) It is the best way to design an algorithm.
C) You must already have a working program in order to do it.
D) It gives valuable insight that you do not get by running the code.

Question 38

What is the output of this code snippet? String str = "ABCabc";
Char ch;
Int i = 0;
While (i < str.length())
{
Ch = str.charAt(i);
If (Character.isLowerCase(ch))
{
System.out.print(i + " ");
}
Else
{
I++;
}
}

A) 3 4 5
B) 3
C) 3 3 3 3 3 ... (infinite loop)
D) 0 1 2

Question 39

When hand-tracing the loop in the code snippet below, which variables are important to evaluate?
Int i = 10;
Int j = 5;
Int k = -10;
Int sum = 0;
While (i > 0)
{
Sum = sum + i + j;
I--;
System.out.println("Iteration: " + i);
}

A) The variables i and j
B) The variables i and sum
C) The variables i, j, and k
D) The variables j and k

Question 40

In the __________ loop header, you can include multiple update expressions, separated by commas, but it is not recommended.

A) do
B) while
C) for
D) do

Question 41

What does the method below return?
Int findSomething (String str)
{
Int position = 0;
While (position < str.length() &&
(str.charAt (position) != 'e'))
{
Position++;
}
Return position;
}

A) The position of the first 'e' in the string or the length of the string if there is no 'e'
B) The position of the last 'e' in the string or the length of the string if there is no 'e'
C) The position of the first character that is not an 'e' in the string or the length of the string if there is no character that is not an 'e'
D) The position of the last character that is not an 'e' in the string or the length of the string if there is no character that is not an 'e'

Question 42

Which of the following statements expresses why the following code is considered bad form? for (rate = 5; years-- > 0; System.out.println(balance))
) . .
I) Unrelated expressions in loop header
II) Doesn't match expected for loop idiom
III) Loop iteration is not clear

A) II and III only
B) I and II only
C) I and III only
D) I, II, and III

Question 43

What does the following code snippet print?
Int a = 120;
Int b = 90;
Int n1 = Math.abs(a);
Int n2 = Math.abs(b);
Int result = 1;
For (int k = 1; k <= n1 && k <= n2; k++)
{
If (n1 % k == 0 && n2 % k == 0)
{
Result = k;
}
}
System.out.println(result);

A) 10
B) 20
C) 30
D) 40

Question 44

What will be printed by the statements below?
Int val = 1;
Int sum = 0;
While (val < 5)
{
Sum = sum + val;
Val++;
}
System.out.print (sum);

A)4
B)5
C)10
D)15

Question 45

Which statement about this code snippet is accurate?
Int years = 50;
Double balance = 10000;
Double targetBalance = 20000;
Double rate = 3;
For (int i = 1; i <= years; i++)
{
If (balance >= targetBalance)
{
I = years + 1;
}
Else
{
Double interest = balance * rate / 100;
Balance = balance + interest;
}
}

A) The loop will run 50 times.
B) The loop will never stop.
C) The loop will run at most 50 times, but may stop earlier when balance exceeds or equals targetBalance.
D) There is a compilation error.

Question 46

What is the output of the following code snippet?
Int counter = 1;
For (double i = 0.01; i <= 1.0; i = i + 0.01)
{
Counter++;
}
System.out.println(counter);

A) 100
B) 49.50
C) 60.5
D) 10

Question 47

What will be printed by the statements below? for (int ctr = 0; ctr < 10; ctr++)
{
System.out.print (ctr + " ");
}

A)0 1 2 3 4 5 6 7 8 9 10
B)0 1 2 3 4 5 6 7 8 9
C)0 2 4 6 8
D)0 1 3 5 7 9

Question 48

Which of the following loops will print the odd numbers between 0 and 20? a. int num = 1;
While (num < 10)
{
Int value = num * 2 - 1;
System.out.print (value + " ");
Num ++;
}
B) int num = 1;
While (num < 20)
{
Int value = num * 2 - 1;
System.out.print (value + " ");
Num ++;
}
C) int num = 1;
While (num < 10)
{
System.out.print (num + " ");
Num += 2;
}
D) int num = 1;
While (num < 20)
{
Num += 2;
System.out.print (num + " ");
}

Question 49

What will be printed by the statements below?
Int val = 1;
Int sum = 0;
While (val < 5)
{
Sum = 0;
Sum = sum + val;
Val++;
}
System.out.print (sum);

A)15
B)10
C)5
D)4

Question 50

What will be printed by the statements below?
Int a = 10;
While (a > 5)
{
A = a - 2;
System.out.print (a + " ");
}

A)10 8 6
B)10 8 6 4
C)8 6
D)8 6 4

Question 51

What is the output of the code below? for (int val = 0; val < 4; val ++)
{
System.out.print ("+");
For (int num = 0; num < val; num++)
{
System.out.print ("0");
}
}

A)+0+00+000+0000
B)+000+000+000+000
C)++0+00+000
D)++++000000

Question 52

What does the following loop compute? Scanner in = new Scanner (System.in);
Int sum = 0;
Int count = 0;
While (in.hasNextInt())
{
Int value = in.nextInt();
If (value > 0)
{
Sum += value;
Count++;
}
}
Double result = (sum * 1.0)/count;

A)The average of all the integers in the input
B)The sum of all the positive integers in the input divided by the number of integers in the input
C) The average of all the positive integers in the input
D)The second smallest value in the input

Question 53

How many times does the following loop execute? for (double d = 1; d != 10; d++)
{
D = d / 3;
System.out.print(d + " ");
}

A) 10
B) 9
C) 8
D) An infinite number of times

Question 54

What will be printed by the statements below?
Int a = 10;
While (a > 5)
{
System.out.print (a + " ");
A = a - 2;
}

A)10 9 8 7 6 5
B)10 8 6 4
C)10 8 6
D)10 8

Question 55

What will be printed by the statements below? for (int ctr = 10; ctr > 5; ctr--)
{
System.out.print (ctr + " ");
}

A)10 9 8 7 6 5
B)10 9 8 7 6
C)5 6 7 8 9 10
D)6 7 8 9 10

Question 56

Which of the following conditions can be added to the code below so it will loop until the value of sum is greater than 100? Scanner in = new Scanner (System.in);
Int sum = 0;
Do {
Sum += in.nextInt();
}
While (/* put condition here */)

A)sum != 0
B)sum <= 100
C)sum > 100
D)sum == 100

Question 57

Which of the following is considered a loop with a problematic condition?

A) for(i = 1; i != n; i++)
B) for (years = n; years > 0; years++)
C) for(i = 1; i <= n; i++)
D) for (int i = 20; i >= 10; i--)

Question 58

Which of the following loops will print the odd numbers between 0 and 20?

A) int num = 1;
While (num < 20)
{
System.out.print (num + " ");
Num += 2;
}
B) int num = 1;
While (num < 20)
{
System.out.print (num + " ");
Num ++;
}
C)
Int num = 0;
While (num < 20)
{
System.out.print (num + " ");
Num += 2;
}
D)
Int num = 1;
While (num < 20)
{
Num += 2;
System.out.print (num + " ");
}

Question 59

Which of the following for loops is illegal?

A) for (int i = 0; ; ) { }
B) for (int i = 0) { }
C) for (int i = 0, k = 1; ; i++) { }
D) for ( ; ; )

Question 60

Is the code snippet written below legal? String s = "1234";
For (int i = 0; i <= 5; i++)
{
System.out.print);
}

A) Yes.
B) No; there should be a semicolon at the end of line 2.
C) No; for i = 4, s.substring(i, i + 1) will result in an StringIndexOutOfBounds error.
D) No; line 4 should have no semicolon at the end.

Question 61

Assume the following variable has been declared and given a value as shown: Random rand = new Random();
Int number = rand.nextInt (27) * 2 + 3;
What are the smallest and largest values number may be assigned?

A)3, 57
B)0, 27
C)3, 55
D)0, 26

Question 62

How many times is the text "Let's have fun with Java." printed when this code snippet is run?
Int i = 0;
Do
{
System.out.println("Let's have fun with Java.");
I++;
If (i % 2 == 0)
{
I = 10;
}
}
While (i <= 10);

A) 1
B) 2
C) 3
D) 10

Question 63

Given the following code snippet, what should we change to have 26 alphabet characters in the string str? String str = "";
For (char c = 'A'; c < 'Z'; c++)
{
Str = str + c;
}

A) int c = 'A'
B) str = c + str;
C) c <= 'Z'
D) Must change to use a do loop

Question 64

What is the output of the following loop?
Int s = 1;
Int n = 1;
Do
{
S = s + n;
N++;
}
While (s < 10 * n);
System.out.println(s);

A) 211
B) 210
C) 120
D) 123

Question 65

Choose the loop that is equivalent to this loop.
Int n = 1;
Double x = 0;
Double s;
Do
{
S = 1.0 / (n * n);
X = x + s;
N++;
}
While (s > 0.01);

A) double x = 0;
Double s = 1;
For (int k = 1; s > 0.01; k++)
{
S = 1.0 / (k * k);
X = x + s;
}
B) double x = 0;
Double s = 1;
For (int k = 1; k < 100; k++)
{
S = 1.0 / (k * k);
X = x + s;
}
C) double x = 0;
Double s = 1;
Int k = 10;
While (s > 0.01)
{
S = 1.0 / (k * k);
X = x + s;
K++;
}
D) double x = 0;
Double s = 10;
Int k = 1;
While (s > 0.01)
{
S = 1.0 / (k * k);
X = x + s;
K++;

Question 66

Which of the following loop(s) could possibly not enter the loop body at all?
I) for loop
II) while loop
III) do loop

A) I only
B) I and II only
C) II and III only
D) I and III only

Question 67

Is the following code snippet legal? boolean b = false;
Do
{
System.out.println("Do you think in Java?");
}
While (b !=

A) Yes, it is legal but does not print anything.
B) Yes, it is legal and prints "Do you think in Java?" once.
B);
C) Yes, it is legal and prints "Do you think in Java?" twice.
D) No, it is not legal and gives a compilation error.

Question 68

Which of the loop(s) test the condition after the loop body executes?
I) for loop
II) while loop
III) do loop

A) I only
B) II only
C) III only
D) II and III

Question 69

Assume the following variable has been declared and given a value as shown: Random rand = new Random();
Which of the following will generate a random integer in the range - 20 to 20, inclusive, where each value has an equal chance of being generated?

A)rand.nextInt (-20, 20)
B)rand.nextInt(20) - 41
C)rand.nextInt (-20) + 40
D)rand.nextInt(41) - 20

Question 70

What is the output of the code snippet given below? String s = "12345";
Int i = 1;
Do
{
If (i > 1)
{
System.out.print);
}
}
While (i < 5);

A) No output
B) No output (infinite loop)
C) 12345
D) 2345

Question 71

How many times does the following loop run?
Int i = 0;
Int j = 1;
Do
{
System.out.println("" + i + ";" + j);
I++;
If (i % 3 == 0)
{
J--;
}
}
While (j >= 1);

A) 1 time
B) 2 times
C) 3 times
D) 4 times

Question 72

Assume the following variable has been declared and given a value as shown: Random rand = new Random();
Double number = rand.nextDouble () * 2 + 3;
What are the smallest and largest values number may be assigned?

A)3)0, 5.0
B)0)0, 6.0
C)-3.0, 3.0
D)0)0, 3.0

Question 73

What for loop can be used in the indicated area so the code will print: ****
***
**
*
For (int val = 0; val < 4; val ++)
{
System.out.print ("+");
// Put for loop here
{
System.out.print ("*");
}
System.out.println ();
}

A) for (int num = 0; num < 4 - val; num++)
B)for (int num = 0; num < val; num++)
C)for (int num = 4; num < val; num++)
D)for (int num = 4; num > 0; num--)

Question 74

How many times does the following loop run?
Int i = 0;
Int j = 1;
Do
{
System.out.println("" + i + ";" + j);
I++;
If (i % 2 == 0)
{
J--;
}
}
While (j >= 1);

A) 0 times
B) 1 times
C) 2 times
D) 4 times

Question 75

What is the output of the code below? for (int val = 0; val < 4; val ++)
{
Int sum = val;
For (int num = 0; num < val; num++)
{
Sum = sum + num;
}
System.out.print (sum + " ");
}

A)0 1 3 6
B)0 1 4 10
C)0 2 5 9
D)0 2 7 16

Question 76

Which loop does not check a condition at the beginning of the loop?
I) The do loop
II) The while loop
III) The for loop

A) I and II
B) I and III
C) I only
D) III only

Question 77

What is the output of the code snippet given below? String s = "abcde";
Int i = 1;
Do
{
If (i > 1)
{
System.out.print);
}
}
While (i < 5);

A) No output
B) No output (infinite loop)
C) abcde
D) bcde

Question 78

What is the output of the code snippet given below? String s = "abcdefghijkl";
Int i = 1;
Do
{
If (i > 2)
{
System.out.print(s.substring (1, i));
}
I++;
}
While (i < 5);

A) abcd
B) bcde
C) bcbcd
D) cdef

Question 79

What is the result when the following code is run? double x = 1;
Double y = 1;
Int i = 0;
Do
{
Y = x / 2;
X = x + y;
I = i + 1;
}
While (x < 2.5);
System.out.print(i + " ");

A) 1
B) 2
C) 3
D) 4

Question 80

Which of the following loops executes the statements inside the loop before checking the condition?

A) for
B) while
C) do
D) do-for