Question

Is it always safe to pass an empty or uninitialised STL container to a function by reference? e.g.

void some_function(deque<string> &passed_by_ref) {

passed_by_ref.push_back("a string");

}

int main() {

deque<string> some_data;

some_function(some_data);

return 0;

}

I haven’t had any problems with this approach, but not sure if there could possibly be any NULL reference issues.

Answer 1

Yes, it’s always safe. deque<T> is not a pointer type – it’s an object type. The standard containers have a default constructor, so, after this statement

deque<string> some_data;

some_data is a correctly constructed empty deque.