当行

cin >> rerun;

执行

时，'\n'留在输入流中.下次您运行

is executed, the '\n' is left in the input stream. Next time you run

getline(cin, input);

您会得到一个空行.

要解决此问题，请添加行

To fix the problem, add the line

cin.ignore();

紧接着

cin >> rerun;

这是您的循环的外观:

do
{
  getline(cin, input);
  cin >> rerun;
  cin.ignore();
}while (rerun == 'y');