/in/foo.cc: In function 'int main()':
/in/foo.cc:9:9: error: unable to find string literal operator 'operator""cin' with 'const char [13]', 'long unsigned int' arguments
   cout<<"用户名："cin>>a;
         ^~~~~~~~~~~~~~~~~
/in/foo.cc:10:9: error: unable to find string literal operator 'operator""cin' with 'const char [10]', 'long unsigned int' arguments
   cout<<"密码："cin>>b;
         ^~~~~~~~~~~~~~