Evaluation order and precedence

Questions 1 to 5 of 8

1. 1. Predict the output of this program. ``cpp #include <iostream> using namespace std; int main() { int n = 4; int r = n-- - 1; cout << n << ' ' << r << endl; return 0; } ``

   4 33 43 34 4
2. 2. What is wrong with this code? ``cpp int j = 1; int s = j++ + j++; ``

   Nothing is wrong, because + always evaluates its left operand first.It is a syntax error, because j++ cannot be used inside an expression.It changes j twice with no order between the two changes, so the result is undefined.It sets s to 3, because the first j++ returns 1 and the second returns 2.
3. 3. In C++17 and later, which side of a = b is evaluated first?

   The left side a, alwaysThe order is left to right for all operators, including =The compiler may pick either order, since the standard does not fix = at allThe right side b, before the left side a
4. 4. Predict the output of this program. ``cpp #include <iostream> using namespace std; int main() { int x = 7 - 3 - 2; int y = 2 * 3 << 1; cout << x << ' ' << y << endl; return 0; } ``

   2 122 80 122 6
5. 5. True or false: in C++, 2 - 3 - 4 groups as 2 - (3 - 4).

   True, because subtraction groups from right to left, like assignment.False, because subtraction groups from left to right, so the value is (2 - 3) - 4, which is -5.True, because parentheses never change the value of an expression.False, because a single expression cannot contain two subtraction operators.