调用从C＃code德尔福DLL的方法 [英] Calling a delphi DLL method from C# Code

问题描述

我试图调用从C＃ASP.NET code德尔福的功能。该函数的声明如下：

I am trying to call a Delphi function from C# ASP.NET code. The function's declaration looks like this:

function SomeFunction(const someString, SomeOtherString: string): OleVariant;

这是我的C＃code我有这个code：

From my C# code I have this code:

[DLLImport(MyDLL.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi)]
public static extern object SomeFunction(string someString, string SomeOtherString);

我每次调用这个方法，并将其保存为一个对象，我得到的P / Invoke错误。我从来没有所谓的非托管code，从我的C＃之前，让我有点不知所措。

Every time I call this Method and store it as an object, I get a P/Invoke error. I've never called unmanaged code from my C# before, so I'm kind of at a loss.

推荐答案

您不能调用的是的DLL函数，因为它采用了德尔福的具体字符串数据类型，它在非英巴卡迪诺产品不等价的。 （即使你的C＃code能比赛的结构的德尔福字符串类型，您还需要分配使用DLL的内存管理器，它几乎可以肯定不会导出的内存。）

You cannot call that DLL function because it uses the Delphi-specific string data type, which has no equivalent in non-Embarcadero products. (Even if your C# code can match the structure of Delphi's string type, you would also need to allocate the memory using the DLL's memory manager, which it almost certainly doesn't export.)

如果您需要更改DLL，然后进行参数的类型PAnsiChar或PWideChar的能力。 （从C＃的声明，它看起来像你想PAnsiChar。）这就是该DLL应该使用所有沿。

If you have the ability to change the DLL, then make the parameters have type PAnsiChar or PWideChar. (From your C# declaration, it looks like you want PAnsiChar.) That's what the DLL should have used all along.

如果你不能改变的DLL，然后写一个使用PAnsiChar或PWideChar，然后转发这些参数原来的DLL德尔福在Delphi或C ++ Builder的包装DLL。或者大声抱怨到DLL的供应商，并要求使用是更友好的其他语言类型的新版本。

If you can't change the DLL, then write a wrapper DLL in Delphi or C++ Builder that uses PAnsiChar or PWideChar and then forwards those parameters to the original Delphi DLL. Or complain loudly to the DLL vendor and request a new version that uses types that are more friendly to other languages.

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