Consider the following code
int main(){ int sum = 0, value = 0; while (std::cin >> value) sum += value; std::cout << "sum is: " << sum << std::endl; return 0; } What is the return value of >> operator, against which while loop is evaluated ? The program terminates on EOF input (Ctrl+Z for windows). Does that mean 0 is stored to cin in case of an EOF ? Does it have anything to do with ASCII value of EOF ?
It returns a reference to basic_ifstream:
basic_istream& operator>> In the context of if, it converts to true unless std::ios_base::failbit or std::ios_base::badbit is set in its state.
cin will be set to failbit of badbit (for example, if cin >> some_integer_variable reads something that is not a number), it will convert to false and the loop will end.According to this reference, the return type is istream&.
It returns a non-const reference to std::cin.
std::istream&, but this question is a duplicate.stringstreamorcindoes not matter, answer holds for allstd::istreams.