Operators & Expressions — Test 1

Correct Answer: D. Undefined behavior
Explanation: The two operands of + are unsequenced relative to each other, and both modify a. That makes the expression undefined behavior, even under C++17. ALSO KNOW (related points): • In C++, what happens with int i = 0; if (i != 0 && 10 / i > 1) {...}? → The condition is false and no division occurs • In C++, what is -7 / 2? → -3 • In C++, what is -7 % 3? → -1 • In C++, what are the values of 6 & 3 and 6 && 3? → 2 and 1 (true) • In C++, what does this print?: int i = 5;; size_t s = sizeof(i++);; cout << i; → 5 • In C++, what is the value of x after int x = (1, 2, 3);? → 3

Correct Answer: B. The condition is false and no division occurs
Explanation: && short-circuits: once the left operand is false, the right operand is never evaluated.

Correct Answer: D. 4.0
Explanation: 5/2 is evaluated first as integer division and gives 2. Then 2 * 2.0 = 4.0. ALSO KNOW (related points): • In C, what is the value of x after int x = 2 + 3 * 4 % 5;? → 4

Correct Answer: D. -4
Explanation: Python's // is floor division and rounds toward negative infinity. ALSO KNOW (related points): • In Python, what are the values of [1] == [1] and [1] is [1]? → True, False

Correct Answer: A. -3
Explanation: Since C++11, integer division truncates toward zero.

Correct Answer: D. 2
Explanation: In Python, the result of % takes the sign of the divisor, consistent with floor division: -7 = 3*(-3) + 2. ALSO KNOW (related points): • What is 2 ** 3 ** 2 in Python? → 512

Correct Answer: B. -1
Explanation: In C++, the result of % takes the sign of the dividend, consistent with truncating division: -7 = 3*(-2) + (-1).

Correct Answer: C. 4
Explanation: * and % have equal precedence and associate left to right: 3*4 = 12, 12%5 = 2, then 2 + 2 = 4.

Correct Answer: A. It assigns 0 to x and the body never executes

Correct Answer: B. 2 and 1 (true)
Explanation: 6 & 3 is bitwise: 110 & 011 = 010 = 2. 6 && 3 is logical, and both operands are nonzero, so the result is true (1).