4.输入缓冲

 #include "iostream"

 using namespace std;

 int main(void)
 {
    char buff='\0';
    string str1;
    for(;buff!='@';)
    {
        str1+=buff;
        cin.get(buff);
    }

    cout<<"you input is: \n"<<str1;
 }

for_cin会把输入存在缓冲区。