My C++ Quiz

Question #70: Which lines below are ill-formed?
51% on 761 times asked

1 #include <iostream>
2
3 struct A
4 {
5   A(int& var) : r(var) {}
6
7   int &r;
8 };
9
10 int main(int argc, char** argv)
11 {
12   int x = 23;
13
14   A a1(x);
15
16   A a2 = a1;
17
18   a2 = a1;
19
20   return 0;
21 }