C＃封送处理C DLL结构布尔

Question

i have some trouble with bool while Marshaling C DLL struct this is code in C DLL

// cbool.h

#ifndef CBOOL_H
#define CBOOL_H

#define false         0
#define true          !false
typedef unsigned char boolean; /* false=0, otherwise true */

#endif


// test.h
#include "cbool.h"

typedef struct
{
    bool a;
    bool b;
  float c;

} BoolStruct;

extern BoolStruct BStruct;
__declspec(dllexport) void  GetBStruct  (BoolStruct* bs);
__declspec(dllexport) void  SetBStruct  (BoolStruct* bs);

// test.c
#include "test.h"

BoolStruct BStruct;
void    GetBStruct  (BoolStruct* bs)
{
*bs = BStruct;
}

void    SetBStruct  (BoolStruct* bs)
{
BStruct = *bs; 
}

and in C#

public struct BoolStruct
{
    public bool a;
    public bool b;
  public float c;

}

BoolStruct bs;

[DllImport(DLL_NAME, EntryPoint = "GetBStruct")]
public static extern void GetBStruct(ref BoolStruct bs);

[DllImport(DLL_NAME, EntryPoint = "SetBStruct")]
public static extern void SetBStruct(ref BoolStruct bs);


bs.a = true;
bs.c = 0.5F;

... set
...get 

But with float type set and get values are correct, while when i set boll (eg true) i receive always false Can you help me?

Answer 1

i try your codes and suggestions, but don't work... I temporarily resolved by editing the file CBool

typedef int boolean; /* false=0, otherwise true */

and it work! in another similar case

typedef struct {

    // don't work!
    //char TestString[5];

    // work!
    int TestString[5];

} MyStruct;

and C#

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]
public struct MyStruct
{
  public MyStruct(uint i)
  {
     // ......
    TestString = new char[5];
  }

  [MarshalAs(UnmanagedType.ByValArray, SizeConst=5)]
  public char[] TestString;  

}

it seems that char and unsigned are the problems, or am I doing wrong somethin 'else, but do not know what

Answer 2

Try:

[StructLayout(LayoutKind.Sequential)]
public struct BoolStruct
{
    [MarshalAs(UnmanagedType.U1)]
    public bool a;

    [MarshalAs(UnmanagedType.U1)]
    public bool b;

    public float c;
}

By default the bool is marshaled as an Int32 in .NET.

And you should always specify the StructLayout when you do PInvoke (but note that for struct it isn't necessary : To reduce layout-related problems associated with the Auto value, C#, Visual Basic, and C++ compilers specify Sequential layout for value types. )

Ah and you forgot the CallingConvention : normally it is Cdecl for C functions:

[DllImport("CPlusPlusSide.dll", EntryPoint = "GetBStruct", CallingConvention = CallingConvention.Cdecl)]
public static extern void GetBStruct(ref BoolStruct bs);

[DllImport("CPlusPlusSide.dll", EntryPoint = "SetBStruct", CallingConvention = CallingConvention.Cdecl)]
public static extern void SetBStruct(ref BoolStruct bs);

(tested both x86 and x64)