Basic utility functions to validate user input.

basicUserInput.hpp

#ifndef MP_BASIC_USER_INPUT
#define MP_BASIC_USER_INPUT

namespace mp {
	
template< typename T >
bool validateInput( std::istream& is, T& value ) {
	std::istream::sentry isOk(is);
	if( isOk ) {
		is >> value;
	} else {
		throw std::runtime_error("An error occured with a std::istream.");
	}
	return is;
}

void flush( std::istream& is ) {
	while( is.good() && is.get != '\n' );
}

template< typename T >
void promptUntilValidInput( std::string prompt, T& value ) {
	using namespace std;

	bool entreValide = false;
	while( !entreValide ) {
		cout << prompt;

		entreValide = validateInput( cin, value );
		if( !entreValide ) {
			cin.clear();
			flush( cin );
		}
	}
	flush( cin );
}

} //namespace mp

#endif //MP_BASIC_USER_INPUT