向DLL添加引用和P /调用它之间存在区别。您只能添加对.NET DLL的引用，因为它是一种以.NET友好的方式直接访问DLL成员的方法。由于两个程序集都使用相同的语言（IL），因此DLL可以轻松地由常规应用程序编译和引用。

There's a difference between adding a reference to the DLL and P/Invoking it. You can only add a reference to .NET DLLs because it is a way of directly accessing the DLL's members in a .NET-friendly way. Since both assemblies are of the same language (IL) the DLL can easily be compiled and referenced by the regular application.

P /调用与之完全不同，因为您可以编组调用到本机DLL，该DLL已被编译为纯机器代码。不能将其添加为引用，因为编译器无法将其链接到.NET代码，因为它仅理解.NET语言和IL。

P/Invoking however is completely different because there you are marshalling calls to a native DLL, which is already compiled into pure machine code. It cannot be added as a reference because the compiler cannot link it to the .NET code since it only understands .NET languages and IL.

将DLL添加到项目中您必须改为将其添加为宽松文件：

To add the DLL to your project you have to add it as a loose file instead:

1. 在中右键单击项目解决方案资源管理器并转到添加>现有项目... 。