C#调用C++

C#调用C++总结

一、C/C++语言的基础

C语言中头文件和cpp文件解析

C语言关键字解析

MFC下的DLL编程学习

C/C++ 函数指针使用总结

二、C#调用C++

        C#调用C++ DLL时类型转换 ：C# 与 C++ 数据类型对照

   //C#调用C++的DLL搜集整理的所有数据类型转换方式,可能会有重复或者多种方案,自己多测试
   //c++:HANDLE(void *) ---- c#:System.IntPtr  
   //c++:Byte(unsigned char) ---- c#:System.Byte  
   //c++:SHORT(short) ---- c#:System.Int16  
   //c++:WORD(unsigned short) ---- c#:System.UInt16  
   //c++:INT(int) ---- c#:System.Int16
   //c++:INT(int) ---- c#:System.Int32  
   //c++:UINT(unsigned int) ---- c#:System.UInt16
   //c++:UINT(unsigned int) ---- c#:System.UInt32
   //c++:LONG(long) ---- c#:System.Int32  
   //c++:ULONG(unsigned long) ---- c#:System.UInt32  
   //c++:DWORD(unsigned long) ---- c#:System.UInt32  
   //c++:DECIMAL ---- c#:System.Decimal  
   //c++:BOOL(long) ---- c#:System.Boolean  
   //c++:CHAR(char) ---- c#:System.Char  
   //c++:LPSTR(char *) ---- c#:System.String  
   //c++:LPWSTR(wchar_t *) ---- c#:System.String  
   //c++:LPCSTR(const char *) ---- c#:System.String  
   //c++:LPCWSTR(const wchar_t *) ---- c#:System.String  
   //c++:PCAHR(char *) ---- c#:System.String  
   //c++:BSTR ---- c#:System.String  
   //c++:FLOAT(float) ---- c#:System.Single  
   //c++:DOUBLE(double) ---- c#:System.Double  
   //c++:VARIANT ---- c#:System.Object  
   //c++:PBYTE(byte *) ---- c#:System.Byte[]  
 

  //c++:BSTR ---- c#:StringBuilder
   //c++:LPCTSTR ---- c#:StringBuilder
   //c++:LPCTSTR ---- c#:string
   //c++:LPTSTR ---- c#:[MarshalAs(UnmanagedType.LPTStr)] string  
   //c++:LPTSTR 输出变量名 ---- c#:StringBuilder 输出变量名
   //c++:LPCWSTR ---- c#:IntPtr
   //c++:BOOL ---- c#:bool   
   //c++:HMODULE ---- c#:IntPtr   
   //c++:HINSTANCE ---- c#:IntPtr  
   //c++:结构体 ---- c#:public struct 结构体{};  
   //c++:结构体 **变量名 ---- c#:out 变量名 //C#中提前申明一个结构体实例化后的变量名
   //c++:结构体 &变量名 ---- c#:ref 结构体 变量名
     
 

  //c++:WORD ---- c#:ushort
   //c++:DWORD ---- c#:uint
   //c++:DWORD ---- c#:int
 

  //c++:UCHAR ---- c#:int
   //c++:UCHAR ---- c#:byte
   //c++:UCHAR* ---- c#:string
   //c++:UCHAR* ---- c#:IntPtr
 

  //c++:GUID ---- c#:Guid
   //c++:Handle ---- c#:IntPtr
   //c++:HWND ---- c#:IntPtr
   //c++:DWORD ---- c#:int
   //c++:COLORREF ---- c#:uint
 



  //c++:unsigned char ---- c#:byte
   //c++:unsigned char * ---- c#:ref byte
   //c++:unsigned char * ---- c#:[MarshalAs(UnmanagedType.LPArray)] byte[]
   //c++:unsigned char * ---- c#:[MarshalAs(UnmanagedType.LPArray)] Intptr
 

  //c++:unsigned char & ---- c#:ref byte
   //c++:unsigned char 变量名 ---- c#:byte 变量名
   //c++:unsigned short 变量名 ---- c#:ushort 变量名
   //c++:unsigned int 变量名 ---- c#:uint 变量名
   //c++:unsigned long 变量名 ---- c#:ulong 变量名
 

  //c++:char 变量名 ---- c#:byte 变量名 //C++中一个字符用一个字节表示,C#中一个字符用两个字节表示
   //c++:char 数组名[数组大小] ---- c#:MarshalAs(UnmanagedType.ByValTStr, SizeConst = 数组大小)] public string 数组名; ushort
 

  //c++:char * ---- c#:string //传入参数
   //c++:char * ---- c#:StringBuilder//传出参数
   //c++:char *变量名 ---- c#:ref string 变量名
   //c++:char *输入变量名 ---- c#:string 输入变量名
   //c++:char *输出变量名 ---- c#:[MarshalAs(UnmanagedType.LPStr)] StringBuilder 输出变量名
 

  //c++:char ** ---- c#:string
   //c++:char **变量名 ---- c#:ref string 变量名
   //c++:const char * ---- c#:string
   //c++:char[] ---- c#:string
   //c++:char 变量名[数组大小] ---- c#:[MarshalAs(UnmanagedType.ByValTStr,SizeConst=数组大小)] public string 变量名;  
 

  //c++:struct 结构体名 *变量名 ---- c#:ref 结构体名 变量名
   //c++:委托 变量名 ---- c#:委托 变量名
 

  //c++:int ---- c#:int
   //c++:int ---- c#:ref int
   //c++:int & ---- c#:ref int
   //c++:int * ---- c#:ref int //C#中调用前需定义int 变量名 = 0;
 

  //c++:*int ---- c#:IntPtr
   //c++:int32 PIPTR * ---- c#:int32[]
   //c++:float PIPTR * ---- c#:float[]
     
 

  //c++:double** 数组名 ---- c#:ref double 数组名
   //c++:double*[] 数组名 ---- c#:ref double 数组名
   //c++:long ---- c#:int
   //c++:ulong ---- c#:int
     
   //c++:UINT8 * ---- c#:ref byte //C#中调用前需定义byte 变量名 = new byte();   
 



  //c++:handle ---- c#:IntPtr
   //c++:hwnd ---- c#:IntPtr
     
     
   //c++:void * ---- c#:IntPtr   
   //c++:void * user_obj_param ---- c#:IntPtr user_obj_param
   //c++:void * 对象名称 ---- c#:([MarshalAs(UnmanagedType.AsAny)]Object 对象名称
 



    
   //c++:char, INT8, SBYTE, CHAR ---- c#:System.SByte   
   //c++:short, short int, INT16, SHORT ---- c#:System.Int16   
   //c++:int, long, long int, INT32, LONG32, BOOL , INT ---- c#:System.Int32   
   //c++:__int64, INT64, LONGLONG ---- c#:System.Int64   
   //c++:unsigned char, UINT8, UCHAR , BYTE ---- c#:System.Byte   
   //c++:unsigned short, UINT16, USHORT, WORD, ATOM, WCHAR , __wchar_t ---- c#:System.UInt16   
   //c++:unsigned, unsigned int, UINT32, ULONG32, DWORD32, ULONG, DWORD, UINT ---- c#:System.UInt32   
   //c++:unsigned __int64, UINT64, DWORDLONG, ULONGLONG ---- c#:System.UInt64   
   //c++:float, FLOAT ---- c#:System.Single   
   //c++:double, long double, DOUBLE ---- c#:System.Double   
 

  //Win32 Types ---- CLR Type   
     
 

  //Struct需要在C#里重新定义一个Struct
   //CallBack回调函数需要封装在一个委托里，delegate static extern int FunCallBack(string str);
 

  //unsigned char** ppImage替换成IntPtr ppImage
   //int& nWidth替换成ref int nWidth
   //int*, int&, 则都可用 ref int 对应
   //双针指类型参数，可以用 ref IntPtr
   //函数指针使用c++: typedef double (*fun_type1)(double); 对应 c#:public delegate double fun_type1(double);
   //char* 的操作c++: char*; 对应 c#:StringBuilder;
   //c#中使用指针:在需要使用指针的地方 加 unsafe
 



  //unsigned char对应public byte
   /*
   * typedef void (*CALLBACKFUN1W)(wchar_t*, void* pArg);
   * typedef void (*CALLBACKFUN1A)(char*, void* pArg);
   * bool BIOPRINT_SENSOR_API dllFun1(CALLBACKFUN1 pCallbackFun1, void* pArg);
   * 调用方式为
   * [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
   * public delegate void CallbackFunc1([MarshalAs(UnmanagedType.LPWStr)] StringBuilder strName, IntPtr pArg);
   *  
   *  
   */

dada

C# 调用C++ DLL  DLLImport说明

C#调用C++ dll，并向调用的函数传递“函数指针”

C#调用C++ Dll 结构体

在C#调用C++的DLL简析（一）——生成非托管dll

C# params 用法简介

初识IntPtr

C# 非托管内存中分配内存注意   Marshal.AllocHGlobal

Marshal.AllocHGlobal 方法的理解

三、常见问题及处理

1、字符串乱码问题

C#调用C++DLL，正确接收与传递中文字符方法 适合回调

C# 调用C++ dll 返回char*调用方式（StringBuilder乱码）   使用MarshalAs(UnmanagedType.LPStr)可解决英文字符串乱码问题，但不能完全解决中文乱码问题。

由于C++默认字符串为utf-8编码，C#使用[MarshalAs(UnmanagedType.LPStr)] StringBuilder  param对应 char * param处理后需要进行utf-8转Unicode的处理，实际开发过程中发现调用Dll取得的字符串可能出现“?”（偶数个汉字正常，奇数个汉字乱码

），这对返回Json字符串的函数影响很大。

推荐使用.net Framework4.7提供的MarshalAs(UnmanagedType.LPUTF8Str)代替MarshalAs(UnmanagedType.LPStr)。使用LPUTF8Str取到的字符串不需转码处理。参见：https://www.e-learn.cn/content/wangluowenzhang/841422

还可以使用自定义封送的方法解决奇数中文乱码的问题

public class UTF8MarshalerForStringBuilder : ICustomMarshaler
    {
        private static UTF8MarshalerForStringBuilder instance;
        object oo;
        public static ICustomMarshaler GetInstance(string cookie)
        {
            if (null == instance)
            {
                instance = new UTF8MarshalerForStringBuilder();
            }
            return instance;
        }

        public IntPtr MarshalManagedToNative(object managedObj)
        {
            if (object.ReferenceEquals(managedObj, null))
                return IntPtr.Zero;
            if (!(managedObj is StringBuilder))
                throw new MarshalDirectiveException("UTF8Marshaler must be used on a StringBuilder.");
            //throw new InvalidOperationException();

            oo = managedObj;

            StringBuilder sb = managedObj as StringBuilder;
            byte[] utf8bytes = new byte[sb.Capacity];
            IntPtr ptr = Marshal.AllocHGlobal(utf8bytes.Length + 1);
            Marshal.Copy(utf8bytes, 0, ptr, utf8bytes.Length);
            Marshal.WriteByte(ptr, utf8bytes.Length, 0);

            return ptr;
        }

        public object MarshalNativeToManaged(IntPtr pNativeData)
        {
            if (pNativeData == IntPtr.Zero)
                return null;

            List<byte> bytes = new List<byte>();
            for (int offset = 0; ; offset++)
            {
                byte b = Marshal.ReadByte(pNativeData, offset);
                if (b == 0)
                    break;
                else
                    bytes.Add(b);
            }
            string str = Encoding.UTF8.GetString(bytes.ToArray(), 0, bytes.Count);
            ((StringBuilder)oo).Append(str);
            return oo;
        }

        public void CleanUpManagedData(object managedObj)
        {
        }

        public void CleanUpNativeData(IntPtr pNativeData)
        {
            Marshal.FreeHGlobal(pNativeData);
        }

        public int GetNativeDataSize()
        {
            return -1;
        }
    }

     调用方法与LPStr类似：

[MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(UTF8MarshalerForStringBuilder))]StringBuilder json

   string封送：

public class UTF8MarshalerForString : ICustomMarshaler
    {
        private static UTF8MarshalerForString instance;
        public static ICustomMarshaler GetInstance(string cookie)
        {
            if (null == instance)
            {
                instance = new UTF8MarshalerForString();
            }
            return instance;
        }
        public void CleanUpManagedData(object managedObj)
        {
        }

        public void CleanUpNativeData(IntPtr pNativeData)
        {
            Marshal.FreeHGlobal(pNativeData);
        }

        public int GetNativeDataSize()
        {
            return -1;
        }

        public IntPtr MarshalManagedToNative(object managedObj)
        {
            if (object.ReferenceEquals(managedObj, null))
                return IntPtr.Zero;
            if (!(managedObj is string))
                throw new MarshalDirectiveException("UTF8Marshaler must be used on a string.");
                //throw new InvalidOperationException();

            byte[] utf8bytes = Encoding.UTF8.GetBytes(managedObj as string);
            IntPtr ptr = Marshal.AllocHGlobal(utf8bytes.Length + 1);
            Marshal.Copy(utf8bytes, 0, ptr, utf8bytes.Length);
            Marshal.WriteByte(ptr, utf8bytes.Length, 0);
            return ptr;
        }

        public object MarshalNativeToManaged(IntPtr pNativeData)
        {
            if (pNativeData == IntPtr.Zero)
                return null;

            List<byte> bytes = new List<byte>();
            for (int offset = 0; ; offset++)
            {
                byte b = Marshal.ReadByte(pNativeData, offset);
                if (b == 0)
                    break;
                else
                    bytes.Add(b);
            }
            return Encoding.UTF8.GetString(bytes.ToArray(), 0, bytes.Count);
        }
    }

2、C#项C++ DLL 传递“函数指针”（委托）引起程序崩溃的问题

【C#】对“xxxx::Invoke”类型的已垃圾回收委托进行了回调。这可能会导致应用程序崩溃、损坏和数据丢失。向非托管代码传递委托时，托管应用程序必须让这些委托保持活动状态，直到确信不会再次调用。    此错误由于传递给C++的委托方法被回收引起，可使用GC.KeepAlive(callback) 可解决这个错误。