Expressions Questions and Answers

Answer: A

Correct answer: Its not zero

if (x = 0) uses the assignment operator, not ==. It assigns 0 to x, and the value of the assignment expression is that same 0, which is false. So the else branch runs and it prints Its not zero - the classic typo that compilers now warn about.

Answer: C

Correct answer: 2

a >> 1 shifts 2 (binary 10) right by one place, giving 1. That is non-zero, so the condition is true and the body runs, printing the value of a - which the shift never changed, since >> yields a new value rather than modifying its operand. The output is 2.

Answer: C

Correct answer: is the best policy

Take the two conditions separately.

• 7 & 8: \(0111 \;\&\; 1000 = 0000\). They share no set bit, so the value is 0 and Honesty is not printed.
• ~7 & 0x000f: \(\sim 0111 = \ldots 11111000\); masking with \(1111\) leaves \(1000 = 8\), which does equal 8.

So only the second printf runs, and the output is is the best policy.

Answer: D

Correct answer: ==

== is the equality operator: it compares and yields 1 or 0, and assigns nothing. The other three are compound assignments - a /= b means a = a / b, and likewise for += and %=.

Answer: D

Correct answer: 6

x *= x + y; means x = x * (x + y) - the whole right-hand side is evaluated first, because compound assignment binds more loosely than +:

There is exactly one modification of x, so nothing here is undefined.

Answer: A

Correct answer: Automatic storage class

A variable declared inside a function with no storage class specifier defaults to auto: it is created on the stack when the block is entered, holds junk unless initialised, and is destroyed on exit. The keyword auto itself is almost never written, precisely because it is the default.