[英]C# Calling C++ DLL Function which returns a struct
我有一個 C++ dll,它定義了一個結構體和一個 dll 調用,如下所示:
typedef const char* FString;
typedef struct {
FString version;
FString build_no;
FString build_type;
FString build_date;
FString build_info;
FString comment;
} FVersionInfo;
extern "C" FAPI_EXPORT FVersionInfo CALLINGCONV fGetVersion(void);
在 C# 方面,我使用動態加載:
[DllImport("kernel32.dll", EntryPoint = "LoadLibrary")]
static extern int LoadLibrary(
[MarshalAs(UnmanagedType.LPStr)] string lpLibFileName);
[DllImport("kernel32.dll", EntryPoint = "GetProcAddress")]
static extern IntPtr GetProcAddress(int hModule,
[MarshalAs(UnmanagedType.LPStr)] string lpProcName);
[DllImport("kernel32.dll", EntryPoint = "FreeLibrary")]
static extern bool FreeLibrary(int hModule);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct FVersionInfo
{
public string Version;
public string Build_No;
public string Build_Type;
public string Build_Date;
public string Build_Info;
public string Comment;
}
[UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)]
public delegate FVersionInfo fGetVersion();
public fGetVersion GetVersion;
FHandle = LoadLibrary(@pName);
IntPtr intPtr;
intPtr = GetProcAddress(FHandle, "fGetVersion");
GetVersion = (fGetVersion)Marshal.GetDelegateForFunctionPointer(intPtr, typeof(fGetVersion));
調用代碼應該是:
FVersionInfo version = new FVersionInfo();
version = GetVersion();
我的第一個問題是,我在 c# 加載部分調用 Marshal.GetDelegateForFunctionPointer 時變成了“System.Runtime.InteropServices.MarshalDirectiveException”。
然后我使用 IntPtr 作為結構返回參數進行了測試,如下所示:
[UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)]
public delegate IntPtr fGetVersion();
所以我讓 Marshal.GetDelegateForFunctionPointer 工作,但后來我在編組方面遇到了同樣的問題:
IntPtr DllValue = new IntPtr();
FVersionInfo version = new FVersionInfo();
DllValue = fGetVersion();
Marshal.PtrToStructure(DllValue, FVersionInfo);
在這里,它在 fGetVersion() 調用時崩潰,帶有“托管調試助手‘PInvokeStackImbalance’”。 我認為這意味着堆棧已損壞(不平衡)。
我已經用結構定義的許多變體進行了測試,但沒有結果。
歡迎任何想法或建議!
感謝您的指導,但我找到了一個可行的解決方案:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)] public struct FVersionInfo { public IntPtr Version; public IntPtr Build_No; public IntPtr Build_Type; public IntPtr Build_Date; public IntPtr Build_Info; public IntPtr Comment; }
所以我通過Marshal.GetDelegateForFunctionPointer
沒有任何問題。
我將使用代碼更改為:
GF.FVersionInfo vi = new GF.FVersionInfo(); vi = gf.GetVersion();
string MyVersion = Marshal.PtrToStringAnsi(VersionInfos.Version);
使用具有 const char * 成員的結構的示例。 在這種情況下,您可以使用自己的 C++ DLL 結構來回傳遞。
// CPP Source code
// ----------------------------------
// Struct definition
struct MyStruct_t {
const char * sStr;
size_t iInt;
};
// ----------------------------------
// C# Source code
// ----------------------------------
// Struct definition
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct MyStruct_t {
public string sStr;
public int iInt;
};
// DLL prototype
[DllImport("Cpp.dll", CallingConvention = CallingConvention.StdCall)]
public static extern void MyFunctionCall(IntPtr MyStruct_t);
// Prepare a struct pointer to pass to DLL
MyStruct_t pMyStruct_t = new MyStruct_t();
IntPtr pMyStructPTR = Marshal.AllocHGlobal(Marshal.SizeOf(pMyStruct_t));
Marshal.StructureToPtr(pMyStruct_t, pMyStructPTR, false);
// Call C++ DLL
MyFunctionCall(pMyStructPTR);
// The DLL updated struct, get the struct
MyStruct_t pMyStruct = (MyStruct_t)Marshal.PtrToStructure(pMyStructPTR, typeof(MyStruct_t));
// Show data
MessageBox.Show(pMyStruct.sStr);
// clean up
if (pMyStructPTR != IntPtr.Zero) { Marshal.FreeHGlobal(pMyStructPTR); pMyStructPTR = IntPtr.Zero; }
// ----------------------------------
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