当用户输入时，输入code> cin.getline 索引，他们也键入换行符，但您的cin没有从输入流中删除它。因此，您对cin.getline的调用将因为剩余的换行符而立即返回。

When the user entered the index, they also typed a newline, but your cin didn't remove it from the input stream. So, your call to cin.getline returns immediately because of the leftover newline.

添加对 cin.ignore 之前，cin.getline将其刷新。

Add a call to cin.ignore before the cin.getline to flush it out.