Visual Studio预编译标头可防止编译器识别std :: cout

Question

我正在尝试在Visual Studio 2017中构建DLL（但它对于静态库的作用相同）;这是我完整的source.cpp文件。

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

void f() { std::cout << "I'm in f!\n"; }

我编译时抱怨

error C2039: 'cout': is not a member of 'std'

如果我删除stdafx.h，则投诉为

fatal error C1010: unexpected end of file while looking for precompiled header. Did you forget to add '#include "stdafx.h"' to your source?

必须有一种编译使用std::的函数的方法！