How Can I get this wrong message?

here is a example from book, when i run it in my visual studio 2013 professional, it show the following error:

#include <iostream>
#include <string>
#include "stdafx.h"

using namespace std;

int main()
{
string mystr;
cout << "What's your name? ";
getline(cin, mystr);
cout << "Hello " << mystr << ".\n";
cout << "What is your favorite team? ";
getline(cin, mystr);
cout << "I like " << mystr << " too!\n";
return 0;
}

1>          Add directive to 'stdafx.h' or rebuild precompiled header
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(5): warning C4627: '#include <string>': skipped when looking for precompiled header use
1>          Add directive to 'stdafx.h' or rebuild precompiled header
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(12): error C2065: 'string' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(12): error C2146: syntax error : missing ';' before identifier 'mystr'
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(12): error C2065: 'mystr' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(13): error C2065: 'cout' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(14): error C2065: 'cin' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(14): error C2065: 'mystr' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(14): error C3861: 'getline': identifier not found
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(15): error C2065: 'cout' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(15): error C2065: 'mystr' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(16): error C2065: 'cout' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(17): error C2065: 'cin' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(17): error C2065: 'mystr' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(17): error C3861: 'getline': identifier not found
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(18): error C2065: 'cout' : undeclared identifier
1>c:\users\boshi xie\documents\visual studio 2013\projects\consoleapplication3\consoleapplication3\consoleapplication3.cpp(18): error C2065: 'mystr' : undeclared identifier
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========