Сочетая приемы из верхнего ответа здесь и этого сайта, я получаю
input.h
#include <ios> // Provides ios_base::failure
#include <iostream> // Provides cin
template <typename T>
T getValidatedInput()
{
// Get input of type T
T result;
cin >> result;
// Check if the failbit has been set, meaning the beginning of the input
// was not type T. Also make sure the result is the only thing in the input
// stream, otherwise things like 2b would be a valid int.
if (cin.fail() || cin.get() != '\n')
{
// Set the error state flag back to goodbit. If you need to get the input
// again (e.g. this is in a while loop), this is essential. Otherwise, the
// failbit will stay set.
cin.clear();
// Clear the input stream using and empty while loop.
while (cin.get() != '\n')
;
// Throw an exception. Allows the caller to handle it any way you see fit
// (exit, ask for input again, etc.)
throw ios_base::failure("Invalid input.");
}
return result;
}
Использование
inputtest.cpp
#include <cstdlib> // Provides EXIT_SUCCESS
#include <iostream> // Provides cout, cerr, endl
#include "input.h" // Provides getValidatedInput<T>()
int main()
{
using namespace std;
int input;
while (true)
{
cout << "Enter an integer: ";
try
{
input = getValidatedInput<int>();
}
catch (exception e)
{
cerr << e.what() << endl;
continue;
}
break;
}
cout << "You entered: " << input << endl;
return EXIT_SUCCESS;
}
Пример прогона
Введите целое число: a
Неверный ввод.
Введите целое число: 2b
Неверный ввод.
Введите целое число: 3
Вы ввели: 3.