If j=5 and k=6, then the value of j++ == k is ___________.

These problems are similar to those you will see on the AP CS A exam.

6-8-1: How many stars are output when the following code is executed?

for (int i = 0; i < 5; i++) { for (int j = 0; j < 5; j++) System.out.println("*"); }

• 10
• The second loop executes 5 times for each of the 5 times the first loop executes, so the answer should be 5 * 5.
• 5
• The second loop executes 5 times for each of the 5 times the first loop executes, so the answer should be 5 * 5.
• 25
• The first loop will execute 5 times, and for each time through, the second loop will execute 5 times. So the answer is the number of times through the first loop times the number of times through the second.
• 50
• The second loop executes 5 times for each of the 5 times the first loop executes, so the answer should be 5 * 5.
• 15
• The second loop executes 5 times for each of the 5 times the first loop executes, so the answer should be 5 * 5.

6-8-2: Which of the following code segments will produce the displayed output?

1 22 333 4444 55555 I. for (int i = 1; i <= 5; i++) { for (int j = i; j > 0; j--) { System.out.print(i); } System.out.println(); } II. for (int i = 0; i < 5; i++) { for (int j = 0; j < i; j++) { System.out.print(i); } System.out.println(); } III. for (int i = 1; i < 5; i++) { for (int j = i; j > 0; j--) { System.out.print(i); } System.out.println(); } IV. for (int i = 1; i < 6; i++) { for (int j = 0; j < i; j++) { System.out.println(i); } } V. for (int i = 0; i < 5; i++) { for (int j = 0; j < i; j++) { System.out.print(i+1); } System.out.println(); }

• I
• This will loop with i changing from 1 to 5 and then for each i, j will loop from i to 0 printing the value of i and then a new line.
• II
• This will loop i from 0 to 4 and j from 0 to i, neglecting to ouput 5.
• III
• This will loop with i changing from 1 to 4 and j from i to 0.
• IV
• This will loop with i changing from 1 to 5 and j from 0 to i but it will print each value on a different line.
• V
• This will loop with i changing from 0 to 4 and j from 0 to i.

6-8-3: What is printed as a result of the following code segment?

for (int k = 0; k < 20; k+=2) { if (k % 3 == 1) System.out.println(k + " "); }

• 0 2 4 6 8 10 12 14 16 18
• This would be correct if we were printing out all of the values of k, not just the ones that have a remainder of 1 when divided by 3.
• 4 16
• This is missing the value 10 (10 divided by 3 does have a remainder of 1).
• 0 6 12 18
• None of these answers have a remainder of 1 when divided by 3.
• 1 4 7 10 13 16 19
• This answer would be correct if k was incremented by 1 instead of 2. K will be 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 in this loop.
• 4 10 16
• This will loop with k having a value of 0 to 18 (it will stop when k = 20). It will print out the value of k followed by a space when the remainder of dividing k by 3 is 1.

6-8-4: Which of the following code segments will produce the displayed output?

11111 2222 333 44 5 I. for (int j = 1; j <= 5; j++) { for (int k = 5; k >= j; k--) { System.out.print(j + " "); } System.out.println(); } II. for (int j = 1; j <= 5; j++) { for (int k = 5; k >= 1; k--) { System.out.print(j + " "); } System.out.println(); } III. for (int j = 1; j <= 5; j++) { for (int k = 1; k <= j; k++) { System.out.print(j + " "); } System.out.println(); } IV. for (int j = 1; j <= 5; j++) { for (int k = 1; k <= 5; k++) { System.out.println(j + " "); } } V. for (int j = 1; j <= 5; j++) { for (int k = j; k <= 5; k++) { System.out.print(k + " "); } System.out.println(); }

• I
• This will loop with j from 1 to 5 and k from 5 to j and print out the value of j and a space. So the first time through the loop it will print 1 five times and the next time it will print out 2 four times and so on.
• II
• This will print out each value from 1 to 5 five times.
• III
• This will loop with j from 1 to 5 and k from 1 times.
• IV
• This will loop j from 1 to 5 and k from 1 to 5, printing each number 5 times.
• V
• This loops with j from 1 to 5 and k from j to 5 and prints out the value of k, printing 1 through 5 on the first line, 2 through 5 on the next, and so on.

6-8-5: What are the values of var1 and var2 after the following code segment is executed and the while loop finishes?

int var1 = 0; int var2 = 2; while ((var2 != 0) && ((var1 / var2) >= 0)) { var1 = var1 + 1; var2 = var2 - 1; }

• var1 = 0, var2 = 2
• This would be true if the body of the while loop never executed. This would have happened if the while check was if var1 != 0 instead of var2 != 0
• var1 = 1, var2 = 1
• This would be true if the body of the while loop only execued one time, but it executes twice.
• var1 = 3, var2 = -1
• This would be true if the body of the while loop executed 3 times, but it executes twice.
• var1 = 2, var2 = 0
• The loop starts with var1=0 and var2=2. The while checks that var2 isn't 0 and that var1/var2 is greater than or equal to zero (0/2=0) so this is equal to zero and the body of the while loop will execute. The variable var1 has 1 added to it for a new value of 1. The variable var2 has 1 subtracted from it for a value of 1. At this point var1=1 and var2=1. The while condition is checked again. Since var2 isn't 0 and var1/var2 (1/1=1) is >=0 so the body of the loop will execute a second time. The variable var1 has 1 added to it for a new value of 2. The variable var2 has 1 subtracted from it for a value of 0. At this point var1=2 and var2=0. The while condition is checked again. Since var2 is zero the while loop stops and the value of var1 is 2 and var2 is 0.
• The loop won't finish executing because of a division by zero.
• 0/2 won't cause a division by zero. The result is just zero.