C++键盘输入，判断yes or no？

#include <iostream>
using namespace std;
int main()
{
  cout << "<y/n>";
  char ch;
  cin >> ch;
  if (ch == 'y' || ch == 'Y')
    cout << "肯定\a\n";
  else if (ch == 'n' || ch == 'N')
    cout << "否定\a\n";
  else
    cout << "退出\a\n";
  system("pause");
  return 0;
}