[英]How to display the values from structures in C# from C++
abc.h file abc.h文件
typedef struct sp_BankNoteTypeList
{
int cim_usNumOfNoteTypes;
struct sp_notetype
{
USHORT cim_usNoteID;
CHAR cim_cCurrencyID[3];
ULONG cim_ulValues;
bool cim_bConfigured;
}SP_CIMNOTETYPE[12];
}SP_CIMNOTETYPELIST,*SP_LPCIMNOTETYPELIST;
BNA_API int BanknoteType(SP_CIMNOTETYPELIST *sp_BankNoteType);
abc.cpp (DLL File) abc.cpp(DLL文件)
int BanknoteType(SP_CIMNOTETYPELIST *sp_BankNoteType)
{
LPWFSCIMNOTETYPE fw_notetypedata;
LPWFSCIMNOTETYPELIST lpNoteTypeList; //output param
hResult = WFSGetInfo(hService, WFS_INF_CIM_BANKNOTE_TYPES, (LPVOID)NULL, 400000, &res);
lpNoteTypeList=(LPWFSCIMNOTETYPELIST)res->lpBuffer;
if(hResult!=0)
{
return (int)hResult;
}
sp_BankNoteType->cim_usNumOfNoteTypes = lpNoteTypeList->usNumOfNoteTypes;
for(int i=0;i<lpNoteTypeList->usNumOfNoteTypes;i++)
{
sp_BankNoteType->SP_CIMNOTETYPE[i].cim_usNoteID = lpNoteTypeList->lppNoteTypes[i]->usNoteID;
sp_BankNoteType->SP_CIMNOTETYPE[i].cim_ulValues = lpNoteTypeList->lppNoteTypes[i]->ulValues;
sp_BankNoteType->SP_CIMNOTETYPE[i].cim_bConfigured = lpNoteTypeList->lppNoteTypes[i]->bConfigured;
sp_BankNoteType->SP_CIMNOTETYPE[i].cim_cCurrencyID[0] = lpNoteTypeList->lppNoteTypes[i]->cCurrencyID[0];
sp_BankNoteType->SP_CIMNOTETYPE[i].cim_cCurrencyID[1] = lpNoteTypeList->lppNoteTypes[i]->cCurrencyID[1];
sp_BankNoteType->SP_CIMNOTETYPE[i].cim_cCurrencyID[2] = lpNoteTypeList->lppNoteTypes[i]->cCurrencyID[2];
}
return (int)hResult;
}
Structure :- 结构体 :-
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct sp_notetype
{
public ushort cim_usNoteID;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
public char[] cim_cCurrencyID;
public ulong cim_ulValues;
public bool cim_bConfigured;
};
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public struct sp_BankNoteTypeList
{
public int cim_usNumOfNoteTypes;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 12)]
public sp_notetype[] SP_CIMNOTETYPE;
};
public sp_notetype[] SP_CIMNOTETYPE;
public sp_BankNoteTypeList SP_CIMNOTETYPELIST;
Function calling:- 功能调用: -
[DllImport(@"abc.dll")]
public static extern int BanknoteType(out sp_BankNoteTypeList SP_CIMNOTETYPELIST);
public string BNA_BankNoteType(out int[] NoteID,out string[]CurrencyID,out string[] Values,out bool[] Configured)
{
NoteID = new int[12];
CurrencyID = new string[12];
Values = new string[12];
Configured = new bool[12];
try
{
trace.WriteToTrace(" Entered in BNA_BankNoteType ", 1);
hResult = BanknoteType(out SP_CIMNOTETYPELIST);
for (int i = 0; i < 12; i++)
{
NoteID[i] = (SP_CIMNOTETYPELIST.SP_CIMNOTETYPE[i].cim_usNoteID);
CurrencyID[i] = (SP_CIMNOTETYPELIST.SP_CIMNOTETYPE[i].cim_cCurrencyID[0]).ToString() + (SP_CIMNOTETYPELIST.SP_CIMNOTETYPE[i].cim_cCurrencyID[1]).ToString() + (SP_CIMNOTETYPELIST.SP_CIMNOTETYPE[i].cim_cCurrencyID[2]).ToString();
Values[i] = (SP_CIMNOTETYPELIST.SP_CIMNOTETYPE[i].cim_ulValues).ToString();
Configured[i] = (SP_CIMNOTETYPELIST.SP_CIMNOTETYPE[i].cim_bConfigured);
}
return DicErrorCode(hResult.ToString());
}
catch (Exception ex)
{
return "FATAL_ERROR";
}
when I try calling them in C# I get garbage value in C#. 当我尝试在C#中调用它时,我在C#中获得了垃圾值。 While I debug them I find proper storing the values. 当我调试它们时,我发现正确存储值。 Any help as to how the values must be passed would be very useful.. Thanks in advance. 关于如何传递值的任何帮助都将非常有用..提前感谢。
The C# declarations are on the right track, it is just that the details are subtly wrong. C#声明是在正确的轨道上,只是细节是巧妙的错误。 A good starting point is this post , shows you how to write some test code to verify that the structure declarations are a good match. 一个很好的起点是这篇文章 ,向您展示如何编写一些测试代码来验证结构声明是否匹配良好。 Doing so on this particular one: 在这个特定的一个这样做:
C++: auto len = sizeof(SP_CIMNOTETYPELIST); // 196 bytes
C# : var len = Marshal.SizeOf(typeof(sp_BankNoteTypeList)); // 296 bytes
Not close, you must get an exact match to have any hope of it marshalling correctly. 不接近,你必须得到完全匹配,以便有正确编组的希望。 The C# declaration for the inner struct should look like this: 内部结构的C#声明应如下所示:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct sp_notetype {
public ushort cim_usNoteID;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
public char[] cim_cCurrencyID;
public uint cim_ulValues;
private byte _cim_bConfigured;
public bool cim_bConfigured {
get { return _cim_bConfigured != 0; }
}
};
[DllImport(@"abc.dll", CallingConvention = CallingConvention.Stdcall)]
public static extern int BanknoteType([Out]out sp_BankNoteTypeList list);
The sp_BankNoteTypeList declaration is okay. sp_BankNoteTypeList声明没问题。 Rerun the test and you should now get 196 bytes in C# as well. 重新运行测试,你现在应该在C#中获得196个字节。 Annotating the changes: 注释更改:
CharSet = CharSet.Ansi
char
, an 8 bit type. 它是一个8位类型的char
的Windows typedef。 CharSet.Auto would have been the right choice if the native structure used WCHAR. 如果原生结构使用WCHAR,CharSet.Auto将是正确的选择。 public uint cim_ulValues;
ULONG
at 32 bits in both 32-bit and 64-bit programs. Windows使用LLP64数据模型 ,在32位和64位程序中保持32位的ULONG
。 That makes uint
the correct C# equivalent instead of ulong. 这使得uint
成为正确的C#等价而不是ulong。 private byte _cim_bConfigured;
bool
is a very tricky type with poor standardization. bool
是一个非常棘手的类型,标准化很差。 It is 1 byte in C++, 4 bytes in C, 2 bytes in COM interop, 1 byte in managed code. 它是C ++中的1个字节,C中的4个字节,COM互操作中的2个字节,托管代码中的1个字节。 The default marshaling assumes BOOL
as the matching native type, the way it is done in the winapi. 默认编组假定BOOL
为匹配的本机类型,就像在winapi中完成的那样。 Declaring it private as a byte with a public property getter is one way to do it and the one I favored here, applying the [MarshalAs(UnmanagedType.U1)] attribute to the field would be another. 将它声明为带有公共属性getter的字节是一种方法,这是我喜欢的方法,将[MarshalAs(UnmanagedType.U1)]属性应用于该字段将是另一种方法。 CallingConvention = CallingConvention.Stdcall
[Out]out sp_BankNoteTypeList list
out
is enough. 这是非常不直观,大多数程序员认为out
就足够了。 But that is a C# language detail that the marshaller does not know about. 但这是编组人员不知道的C#语言细节。 Copying back has to be explicitly requested, the structure is not "blittable". 必须明确要求复制,结构不是“blittable”。 Or in other words, the native layout is not the same as the internal managed layout. 或者换句话说,本机布局与内部托管布局不同。 The ByValArray makes that inevitable. ByValArray使这不可避免。 Quite a laundry-list, I hope I got them all. 相当一个洗衣清单,我希望我得到它们。 Getting the structure sizes the same is 95% of the battle. 获得相同的结构大小是战斗的95%。
I've recreated the C++ part, since I got errors related to WFSGetInfo
and its related structs, I'm populating fields with some random data (a note about char[3]
field: I'm populating it with 3 random uppercase letters). 我重新创建了C ++部分,因为我得到了与WFSGetInfo
及其相关结构相关的错误,我用一些随机数据填充字段(关于char[3]
字段的注释:我用3个随机大写字母填充它) 。 With inspiration from MSDN and many other questions from SO , I've identified a list of problems in the code; 从MSDN的灵感和SO的许多其他问题,我已经确定了代码中的问题列表; after fixing those problems, I was able to get the right data out from C# . 在解决了这些问题后,我能够从C#中获取正确的数据。 As a note, I'm using VStudio2015 . 请注意,我正在使用VStudio2015 。
Couple of ground notes: 几个地面笔记:
BNA_API
for me is __declspec(dllexport)
我的BNA_API
是__declspec(dllexport)
The function declaration is placed inside a 函数声明放在一个
#if defined(__cplusplus) extern "C" { #endif // Function declaration comes here #if defined(__cplusplus) } #endif
block, to avoid C++ name mangling . 阻止,以避免C ++名称损坏 。 For more details, check [MSDN]: Decorated Names 有关更多详细信息,请查看[MSDN]:装饰名称
Problems: 问题:
__cdecl
while the C# marshaler uses __stdcall
. 调用约定不匹配(这在我的情况下抛出异常):默认情况下, C ( C ++ )使用__cdecl
而C#封送程序使用__stdcall
。 That doesn't work well, it corrupts the stack when push ing/ pop ping arguments. 这不能很好地工作,它会在推送 / 弹出 ping参数时破坏堆栈。 In order to fix this you must change the default in one place only : 要解决此问题,您必须仅在一个地方更改默认值:
BNA_API int
__stdcall
BanknoteType(SP_CIMNOTETYPELIST *sp_BankNoteType);
C ++ : BNA_API int
__stdcall
BanknoteType(SP_CIMNOTETYPELIST *sp_BankNoteType);
- this is the method I chose - 这是我选择的方法 DllImport(@"abc.dll", CallingConvention = CallingConvention.Cdecl)]
- this works as well C# : DllImport(@"abc.dll", CallingConvention = CallingConvention.Cdecl)]
- 这也适用 struct sp_notetype
's C# definition, you should have: public
uint
cim_ulValues;
所以,在struct sp_notetype
的C#定义中,你应该有: public
uint
cim_ulValues;
. 。 Check [MSDN]: Marshaling Arguments for the complete list 检查[MSDN]:Marshaling Arguments以获取完整列表 Charset
of your structures - in C , char
(8bit wide) is used -, change it from Charset.Auto
to Charset.Ansi
. (可能是前一个的变体)你的结构的Charset
集 - 在C , char
(8位宽)中使用 - ,将它从Charset.Auto
更改为Charset.Ansi
。 Check [SO]: C# calling C DLL, pass char * as parameter not correct 检查[SO]:C#调用C DLL,传递char *作为参数不正确
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