AP CSA Primitives & Casting Practice Test

AP CSA Practice Test: Primitives, Casting & Expressions

Unit 1: Using Objects | 10 Questions | AP Computer Science A

Question 1

What is the value of result after the following code executes?

int a = 17; int b = 5; int result = a / b + a % b;
A3
B4
C5
D6

Integer division: 17 / 5 = 3 (truncates decimal). Modulus: 17 % 5 = 2 (remainder). So result = 3 + 2 = 5.

Question 2

Which of the following expressions evaluates to 2.5?

A5 / 2
B(double) 5 / 2
C(double) (5 / 2)
D5 / 2.0 + 0 cast to int

A: 5/2 = 2 (integer division). B: Cast 5 to double first, then 5.0/2 = 2.5. Correct! C: 5/2 = 2 first, then cast to 2.0. D: 5/2.0 = 2.5 but casting to int gives 2.

Question 3

What is printed by the following code?

int x = 5; System.out.println(x++ + ++x);
A10
B11
C13
D12

x++ uses current value (5), then increments x to 6. ++x increments x to 7, then uses that value. So: 5 + 7 = 12.

Question 4

Consider the following code segment. Which statement about the error is correct?

double price = 19.99; int dollars = price;
ACompile error: possible lossy conversion from double to int
BRuntime error: cannot convert double to int
CNo error; dollars equals 19
DNo error; dollars equals 20

Java does not allow implicit narrowing conversions. Assigning a double to an int without an explicit cast causes a compile-time error. You must write int dollars = (int) price; to compile.

Question 5

What is the value of n after this code runs?

int n = 10; n += n-- - --n;
A10
B11
C12
D8

Compound assignment evaluates left side first: n=10. Then n-- returns 10, n becomes 9. Then --n decrements to 8 and returns 8. Expression: 10 - 8 = 2. Finally: n = 10 + 2 = 12.

Question 6

Consider the following statements about Java primitive types. Which are TRUE?

I. An int can store any value a short can store. II. A float can store any value an int can store exactly. III. A long can store any value an int can store.
AI only
BI and III only
CI, II, and III
DII and III only

I: True - int (32-bit) can hold all short (16-bit) values. II: False - float has only 24 bits of precision, so large int values (beyond 2^24) lose precision. III: True - long (64-bit) can hold all int (32-bit) values exactly.

Question 7

What value is stored in result?

int result = 3 + 4 * 2 - 8 / 4 + 1;
A4
B6
C8
D10

Follow operator precedence: * and / before + and -. So: 4*2=8, 8/4=2. Then left to right: 3 + 8 - 2 + 1 = 10.

Question 8

The following code is intended to calculate 20% of a price. What is the problem?

int price = 50; double discount = price * 20 / 100;
AInteger division causes discount to be 10.0 instead of 10.0 (no issue for this input, but fails for price=55)
BCompile error: cannot multiply int by int
CRuntime error: division by zero
DThere is no problem; the code works correctly for all prices

The expression price * 20 / 100 uses integer arithmetic throughout. For price=50: 50*20=1000, 1000/100=10, which happens to be correct. But for price=54: 54*20=1080, 1080/100=10 (should be 10.8). Integer division truncates the decimal. Fix: use price * 20.0 / 100 or price * 0.20.

Question 9

What is printed?

int a = 7, b = 3; System.out.println(a % b + " " + a / b);
A1 2.33
B2 1
C1 2
D1.0 2.0

7 % 3 = 1 (remainder when 7 divided by 3). 7 / 3 = 2 (integer division). Output: "1 2".

Question 10

Which line contains an error that will NOT compile?

int x = 5; // Line 1 double y = x; // Line 2 int z = y; // Line 3 int w = (int) y; // Line 4
ALine 2
BLine 3
CLine 4
DAll lines compile successfully

Line 1: Valid int declaration. Line 2: Valid - int to double is widening (automatic). Line 3: Error - double to int is narrowing and requires explicit cast. Line 4: Valid - explicit cast provided.

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