从非托管C ++创建DLL [英] Create DLL from unmanaged C++
问题描述
我目前有一个以非托管C ++编写的控制台应用程序，源代码由入门点 main 和其他一些功能组成。我需要从这个代码创建一个DLL，以便我可以使用其他项目，特别是从托管的C ++。 （另一个问题：为此，我必须编写一个包装类吗？）
I currently have a console application written in unmanaged C++, the source code consists of an entry-point main and some other functions. I need to create a DLL from this code so that I can use it from other projects, specifically from managed C++. (Another question: would I have to write a wrapper class for this purpose?)
正如我所知，托管/非托管C ++和创建DLL没有任何意义，我遵循< a href =http://msdn.microsoft.com/en-us/library/ms235636(v=vs.80).aspx =nofollow noreferrer>本教程，并设法获得一个简单的Hello World DLL通过使用VS2010（没有CMake）启动并运行。
As I know next to nothing of managed/unmanaged C++ and creating DLLs, I followed this tutorial and managed to get a simple Hello World DLL up and running by using only VS2010 (no CMake).
然而，我的这个项目有很多依赖（例如点云库），所以我通常使用CMake生成Visual Studio 2010解决方案，然后构建为可执行文件，如 PCL教程。如何使用CMake构建一个将构建为DLL的VS2010项目？
However, this project of mine has a lot of dependencies (e.g. Point Cloud Library), and so I normally use CMake to generate the Visual Studio 2010 solution that then builds into an executable, as described in the PCL Tutorial. How can I use CMake to build a VS2010 project that will build into a DLL?
总结我的问题：
- 我有一个非托管C ++代码的项目需要很多依赖。
- 我想从这个代码中创建一个DLL，可以从管理C ++。
额外的信息：
Windows 7，Visual Studio 2010 Ultimate，CMake 2.8.10.2
Extra information: Windows 7, Visual Studio 2010 Ultimate, CMake 2.8.10.2
编辑：
我使用CMake与你的行改变，它的工作正常。这是我添加到我的头文件中，我在正确的轨道上？
I used CMake with your line changed, and it worked as expected. This is what I have since added to my header file, am I on the right track?
MyCode.h
#ifdef MyLib_EXPORTS
#define API_DECL __declspec( dllexport )
#else
#define API_DECL __declspec( dllimport )
#include <iostream>
#include <pcl/...>
etc...
API_DECL void myFirstFunction();
API_DECL void mySecondFunction();
#endif
MyCode.cpp：我没有对源文件进行任何更改，我应该做什么？
MyCode.cpp: I have not made any changes to the source file, should I make any?
推荐答案
不幸的是，我无法帮助您使用托管代码部分，但这是您如何创建一个DLL在CMake中：
Unfortunately, I cannot help you with the managed code part, but this is how you create a DLL in CMake:
首先，而不是使用
`ADD_EXECUTABLE( YourLib SHARED yourclass.cpp yourclass.h )`
.txt ，使用
in your CMakeLists.txt, use
`ADD_LIBRARY( YourLib SHARED yourclass.cpp yourclass.h )`
这将配置解决方案来创建一个DLL而不是可执行文件。
This will configure the solution to create a DLL rather than an executable.
但是，为了能够将这个DLL与您的项目一起使用，您需要导出要使用的符号。为此，您需要将 __ declspec（dllexport）添加到您的类和/或函数声明中。然后构建库将产生两个文件，一个。 dll 和一个 .lib 。后一种是您想在其他项目中使用此库时所需的所谓导入库。运行时将需要 .dll 。
However, to be able to use this DLL with your projects, you need to export the symbols you want to use. To do this, you need to add __declspec( dllexport ) to your class and/or function declarations. Building the library will then yield two files, a .dll and a .lib. The latter one is the so-called import library that you need when you want to use this library in your other projects. The .dll will be required at runtime.
但是：当您想使用库时，需要使用 __ declspec（dllimport）（而不是 dllexport ）。为了避免使用两个头文件，通常的方法是使用预处理器。在您的库项目中提供一个 YourLibrary_EXPORTS define 可以帮助您。
However: When you want to use your library, you need to use __declspec( dllimport) (rather than dllexport). To avoid using two header files, the usual way to do this is to use the preprocessor. CMake actually helps you by providing a YourLibrary_EXPORTS define in your library project.
总结：
#ifndef YOUR_CLASS_H
#define YOUR_CLASS_H
#ifdef YourLib_EXPORTS
#define API_DECL __declspec( dllexport )
#else
#define API_DECL __declspec( dllimport )
#endif
class APIDECL YourClass {
void foo();
void bar();
};
#endif // YOUR_CLASS_H
编辑：
如果你想要能够使用C（和能够使用C函数的语言）的这些函数，你应该用 externC{
extern "C" {
API_DECL void myFirstFunction();
API_DECL void mySecondFunction();
}
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