C#-方法的类型签名与PInvoke不兼容 [英] C# - Method's type signature is not PInvoke compatible

问题描述

我正在尝试在C#(2010)中使用VC ++(2003)dll 从C#调用dll方法时出现此错误 方法的类型签名与PInvoke不兼容"

I am trying to use the VC++ (2003) dll in C# (2010) When am calling the method of dll from c# am getting this error "Method's type signature is not PInvoke compatible"

I am returning the structure from VC++
Code:
struct SLFData
{
public:
char ByLat[10];
char ByLong[10];
};

And I am marshalling in C# 
Code:
 [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
    public struct SLFData
    {
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)]
        public char[] ByLat;     
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)]
        public char[] ByLong;
    };

再次出现相同的错误！ 我在这里想念什么? 谁能帮我Plzz

Yet again I get the same error! What am I missing here? Can anybody help me Plzz

推荐答案

您说您正在使用该结构作为返回值. 文档说:

You say that you are using the struct as a return value. The documentation says:

从平台调用调用返回的结构必须是可蓝调的类型.平台调用不支持将不可引用的结构作为返回类型.

Structures that are returned from platform invoke calls must be blittable types. Platform invoke does not support non-blittable structures as return types.

您的结构不可复制.因此，您不能将其用作函数返回类型.

Your struct is not blittable. So you cannot use it as a function return type.

最简单的方法是通过函数的参数返回结构.更改C ++函数以接受类型为SLFData*的参数，并使调用者传递C ++函数填充的结构的地址.在C#端，您将结构作为out参数传递.

The simplest way to proceed is to return the struct via a parameter of the function. Change the C++ function to accept a parameter of type SLFData* and have the caller pass in the address of a struct which the C++ function populates. On the C# side you pass the struct as an out parameter.

FWIW，您的结构声明错误.首先，C#char为两个字节宽.最好这样做:

FWIW, your struct declaration is wrong. For a start C# char is two bytes wide. It's best done like this:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct SLFData
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
    public string ByLat;     
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
    public string ByLong;
};

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