AP Computer Science midterm study guide

Consider the following code segment. int a = 1; String result = ""; while (a < 20) { result += a; a += 5; } System.out.println(result); What, if anything, is printed as a result of executing the code segment?

161116

In the following expression, sweet, salty, and sour are properly declared and initialized boolean variables. sweet && (salty || sour) Which of the following expressions is equivalent to the expression above?

(sweet && salty) || (sweet && sour)

Consider the following code segment. String str = "AP-CSA"; for (int i = 0; i < str.length(); i++) { if (str.substring(i, i + 1).equals("A")) { System.out.print(i + " "); } } What is printed as a result of executing the code segment?

0 5

Consider the following code segment. int m = 8; int n = 3; if (m + n > 10) { System.out.print(m + n); } if (m - n > 0) { System.out.print(m - n); } What, if anything, is printed as a result of executing the code segment?

115

Consider the following code segment. int count = 0; int number = 20; while (number > 0) { number = number / 2; count++; } What will be the value of count after executing the code segment?

5

Consider the following code segment. int a = 100; while (a > 1) { System.out.println("$"); a /= 2; } How many $'s are printed as a result of executing the code segment?

6

Consider the following code segment. String first = new String("duck"); String second = new String("duck"); String third = new String("goose"); if (first == second) { System.out.print("A"); } else if (second == third) { System.out.print("B"); } else if (first.equals(second)) { System.out.print("C"); } else if (second.equals(third)) { System.out.print("D"); } else { System.out.print("E"); } What is printed as a result of executing the code segment?

C

Consider the method digitSum below, which takes a positive integer parameter as input. public int digitSum(int num) { int total = 0; while (num > 0) { total += num % 10; num /= 10; } return total; } Which of the following code segments could replace the while loop in the method digitSum without changing the value returned by the method? (I.) for (int h = 0; h < num; h++) { total += num % 10; num /= 10; } (II.) for (int j = num; j > 0; j--) { total += j % 10; } (III.) for (int k = num; k > 0; k /= 10) { total += k % 10; }

III only

Consider the following code segment. for (int i = 0; i < 5; i++) // Line 1 { for (int j = 0; j < 5; j++) { int k = i + j; System.out.print(k + " "); } } Which of the following best describes the result of changing i < 5 to i > 5 in line 1?

Nothing will be printed because the body of the outer for loop will not execute at all.

Consider the following code segments, which differ only in their loop header. Code Segment I for (int i = 0; i < 10; i++) { System.out.print( "*" ); } Code Segment II for (int i = 1; i <= 10; i++) { System.out.print( "*" ); } Which of the following best explains how the difference in the two loop headers affects the output?

The output of the code segments is the same because the loops in both code segments iterate 10 times.

Consider the following code segment. for (int j = 0; j < 4; j++) { for (int k = 0; k < j; k++) { System.out.println("hello"); } } Which of the following best explains how changing the inner for loop header to for (int k = j; k < 4; k++) will affect the output of the code segment?

The string "hello" will be printed four additional times because the inner loop will iterate one additional time for each iteration of the outer loop.

Consider the following code segment. int n = 6; for (int i = 1; i < n; i = i + 2) // Line 2 { System.out.print(i + " "); } Which of the following best explains how changing i < n to i <= n in line 2 will change the result?

There will be no change to the program output because the loop will iterate the same number of times.

Consider the following code segment. int a = 1; while (a <= 2) { int c = 1; while (/* missing condition */) { System.out.print("*"); c++; } a++; } The code segment is intended to print "******". Which of the following can be used to replace /* missing condition */ so that the code segment works as intended?

c <= 3

Consider the following code segment. for (int k = 0; k < 4; k++) { /* missing loop header */ { System.out.print(k); } System.out.println(); } The code segment is intended to produce the following output. 0 11 222 3333 Which of the following can be used to replace /* missing loop header */ so that the code segment will work as intended?

for (int h = k; h >= 0; h--)

Consider the following code segment. int total = 0; for (int k = 0; k <= 100; k += 2) { total += k; } Which of the following for loops could be used to replace the for loop in the original code segment so that the original and the revised code segments store the same value in total?

for (int k = 1; k <= 101; k += 2) { total += k - 1; }

Consider the following code segment. String myString = new String("my string"); String yourString = new String(); yourString = "my string"; boolean dotEquals = myString.equals(yourString); boolean equalsEquals = (myString == yourString); System.out.print(dotEquals + " " + equalsEquals); What is printed as a result of executing the code segment?

true false

Consider the following code segment. String str1 = new String("Happy"); String str2 = new String("Happy"); System.out.print(str1.equals(str2) + " "); System.out.print(str2.equals(str1) + " "); System.out.print(str1 == str2); What is printed as a result of executing the code segment?

true true false

Consider the following incomplete code segment, which is intended to print the sum of the digits in num. For example, when num is 12345, the code segment should print 15, which represents the sum 1 + 2 + 3 + 4 + 5. int num = 12345; int sum = 0; /* missing loop header */ { sum += num % 10; num /= 10; } System.out.println(sum); Which of the following should replace /* missing loop header */ so that the code segment will work as intended?

while (num > 0)

Consider the following code segment, which is intended to store the sum of all multiples of 10 between 10 and 100, inclusive (10 + 20 + ... + 100), in the variable total. int x = 100; int total = 0; while( /* missing code */ ) { total = total + x; x = x - 10; } Which of the following can be used as a replacement for /* missing code */ so that the code segment works as intended?

x >= 10