导入C ++ DLL在C＃项目 [英] Importing c++ dll in c# project

问题描述

我进口一些C ++ DLL到C＃项目中，我使用Visual Studio 2010中我已经succeded导入使用功能内置型，但是我得到的错误，当我试图处理结构。这是一个简单的例子：

I am importing some c++ dll into a c# project, I am using visual studio 2010. I have succeded to import function that are using built-in type, however I am getting error when I have tried to deal with structure. This is a simple example:

C ++代码

typedef long int TDate;

typedef struct _TMDYDate
{
    long month;                         /* In range [1,12] */
    long day;                           /* In range [1-31] */
    long year;                          /* In range [1600-] */
} TMonthDayYear;

int JpmcdsDateToMDY
    (TDate date,                        /* (I) TDate format */
     TMonthDayYear *mdyDate);

和我已经翻译到C＃为：

and I have translated to c# as:

   [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct TMonthDayYear {
    public int month;
    public int day;
    public int year;
}

public partial class NativeMethods {

    [System.Runtime.InteropServices.DllImportAttribute("MyDll.dll", EntryPoint="JpmcdsDateToMDY")]
public static extern  int JpmcdsDateToMDY(int date, ref TMonthDayYear mdyDate) ;

}

当我尝试在我的测试程序运行的功能我得到这个错误：

when I try to run the function in my test program I get this error:

未处理的异常：System.AccessViolationException：尝试读取或写入受保护的内存。这通常是指示其他内存已损坏。在CsharpWrapper.NativeMethods.JpmcdsDateToMDY（的Int32日期，TMonthDayYear&安培; MDY日）

该结构的声明在堆栈中，我认为（也许）是问题但我仍然得到，即使我有改变TMonthDayYear上课同样的错误。

The struct are declare in the stack and I thought (maybe) was the problem but I am still getting the same error even though I have change TMonthDayYear to class.

我在做什么错了？

感谢您的帮助。

推荐答案

您必须使用CallingConvention属性的函数[DllImport]属性，这是CDECL因为你没有在本地函数声明中使用__stdcall。虽然这是错误的，它不是为AV一个很好的解释。您需要调试C代码，该AV表明，它有一个指针错误。项目+属性，调试，勾选启用非托管代码调试，并设置在C函数中设置断点。

You have to use the CallingConvention property in the [DllImport] attribute, this is Cdecl since you didn't use __stdcall in the native function declaration. While that's wrong, it is not a great explanation for the AV. You need to debug the C code, the AV suggests it has a pointer bug. Project + Properties, Debug, tick "Enable unmanaged code debugging" and set a breakpoint on the C function.

坦率地说，一个日期转换这样应该写在纯C＃

Frankly, a date conversion like this should be written in pure C#.

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