调用非托管函数char返回char*

Question

我在非托管C/C++代码(dll)中有一个函数,它返回一个包含char数组的结构.我创建了C#struct来接收调用该函数的返回值.并且调用此函数的uppon得到'System.Runtime.InteropServices.MarshalDirectiveException'

这是C声明:

typedef struct T_SAMPLE_STRUCT {
int num;
char text[20];
} SAMPLE_STRUCT;

SAMPLE_STRUCT sampleFunction( SAMPLE_STRUCT ss );

这是C#声明:

struct SAMPLE_STRUCT
{
    public int num;
    public string text;
}

class Dllwrapper
{
    [DllImport("samplecdll.dll")]
    public static extern SAMPLE_STRUCT sampleFunction(SAMPLE_STRUCT ss);

}

我使用1字节ASCII.

有没有人有关于如何做到这一点的提示或解决方案？

Answer 1

转换C数组成员的技巧是使用MarshalAs(UnmanagedType.ByValTStr).这可以用来告诉CLR将数组编组为内联成员与普通非内联数组.请尝试以下签名.

[System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, CharSet=System.Runtime.InteropServices.CharSet.Ansi)]
public struct T_SAMPLE_STRUCT {

    /// int
    public int num;

    /// char[20]
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=20)]
    public string text;
}

public partial class NativeMethods {

    /// Return Type: SAMPLE_STRUCT->T_SAMPLE_STRUCT
    ///ss: SAMPLE_STRUCT->T_SAMPLE_STRUCT
    [System.Runtime.InteropServices.DllImportAttribute("<Unknown>", EntryPoint="sampleFunction")]
public static extern  T_SAMPLE_STRUCT sampleFunction(T_SAMPLE_STRUCT ss) ;

}

此签名由CodePlex上提供的PInovke Interop Assistant(链接)提供给您.它可以自动将大多数PInvoke签名从本机代码转换为C#或VB.Net.