cin.getline()

在使用函数cin.getline()时可能会存在问题，例如：

using namespace std;
    char city[20];
    cout<<"Input your city:"<<endl;
    cin.getline(city,3);
    cout<<"Hi,"<<city<<endl;
    cin.getline(city,20);
    cout<<"Hello "<<city<<endl;
return 0;

• 运行结果：
  
• cin.getline(city,3)指定最多只能接收2个字符
• 当输入的字符比指定的多，getline会设置失效位，接下来的输入被阻断

解决办法

using namespace std;
    char city[20];
    cout<<"Input your city:"<<endl;
    cin.getline(city,3);
    cin.clear();//恢复输入
    cout<<"Hi,"<<city<<endl;
    cin.getline(city,20);
    cout<<"Hello "<<city<<endl;
return 0;

• 运行结果：
  

• 即cin.getline(city,20)；接收输入流中的剩余部分

若要再次输入需要写两次cin.getline(city,20):

 using namespace std;
    char city[20];
    cout<<"Input your city:"<<endl;
    cin.getline(city,3);
    cin.clear();//恢复输入
    cout<<"Hi,"<<city<<endl;
    cout<<"Input your city again:"<<endl;
    cin.getline(city,20);
    cin.getline(city,20);
    cout<<"Hello "<<city<<endl;
 return 0;

• 运行结果：