I have an annoying problem with the C ++ function that I wrote, and the purpose of which is to validate user input. The function reads user input, checks if it is a number and, if so, if it is in the range [min, max].
The problem occurs when I call a template function with an unsigned type, for example size_t, and the input is a negative number. The string stream converts the string to something like 4294967291. I can see that the program converts the data to a value close to the maximum value of the unsigned data type (defined in the numeric_limits header), but my question is, why ifshould I stop at sstream >> value?
My code is:
template <class T>
T getNumberInput(std::string prompt, T min, T max) {
std::string input;
T value;
while (true) {
try {
std::cout << prompt;
std::cin.clear();
std::getline(std::cin, input);
std::stringstream sstream(input);
if (input.empty()) {
throw EmptyInput<std::string>(input);
} else if (sstream >> value && value >= min && value <= max) {
std::cout << std::endl;
return value;
} else {
throw InvalidInput<std::string>(input);
}
} catch (EmptyInput<std::string> & emptyInput) {
std::cout << "O campo não pode ser vazio!\n" << std::endl;
} catch (InvalidInput<std::string> & invalidInput){
std::cout << "Tipo de dados inválido!\n" << std::endl;
}
}
}
Thank you for your time!