如何在C中使用DLL C ++（VB）？

本文介绍了如何在C中使用DLL C ++（VB）？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我在一个例子中编写了这段代码。 我在Visual Basic C ++中编写了这段代码。现在我想用C调用它。 我希望得到20分C. 你能指导吗？ 谢谢。 我用C ++创建了这个Dll： 我尝试了什么：

I wrote this code in an example. I wrote this code in Visual Basic C++. Now I want to call it in C. I want to get 20 in C. Can you guide? thanks. I created this Dll in C++ : What I have tried:

extern "C" __declspec(dllexport) int number(int a); int DllMain() { a=20; return (a); }

推荐答案

如果你真的使用Visual Basic，那么根本不容易。 首先，Visual Basic对C ++一无所知 - 它是一种托管的.NET语言，这意味着你需要在机器上安装和加载适当的.NET框架才能使用它。 C不是托管的，它是原生的 - 它对.NET一无所知 - 所以它变得非常复杂：从C调用C＃ - 堆栈溢出 [ ^ ]（C＃是另一种.NET语言，它与VB完全相同）。 如果你想从C调用本机C ++函数，那就更容易了：混音C和C ++代码同一计划 [ ^ ] 只是不要再使用Visual Basic一词 - 它与C或C ++无关！ If you are genuinely using Visual Basic, then "not at all easily". First off, Visual Basic has nothing at all to d with C++ - it's a managed .NET language, which means you need the appropriate .NET framework installed and loaded on the machine in order to use it. C is not managed, it's native - it knows nothing at all about .NET - so it gets very complicated: Calling C# from C - Stack Overflow[^] (C# is another .NET language, and it's exactly the same procedure for VB). If you want to call native C++ functions from C, that's easier: Mixing C and C++ Code in the Same Program[^] Just don;t use the term "Visual Basic" again - it's nothing to do with C or C++!

你不能除非您提供适当的界面，否则请使用任何语言。首次加载库时，Windows会调用DllMain，它不是用户函数。请参阅创建和使用动态链接库（ C ++）| Microsoft Docs [ ^ ]。 此外没有 Visual Basic C ++ 这样的东西。 You cannot use it in any language unless you provide a proper interface. DllMain is called by Windows when the library is first loaded, it is not a user function. See Creating and Using a Dynamic Link Library (C++) | Microsoft Docs[^]. Also there is no such thing as Visual Basic C++.

你编写的代码通过声明数字函数有一个主要缺陷，但是实现了main。在标题和c文件中的实现中写下声明。 必须具有与声明的相同的签名。所以： The code that you wrote has a main flaw by declaring the number function, but implementing the the main. Write the declaration in the header and the implementation in the c-file. It MUST have the same signature as declared. So: int number(int a) { a=20; return (a); }

通过 GetProcAdress 非常简单，但请注意签名和每个错误。

Calling dlls via GetProcAdress is very easy, But take care on the signature and every error.