C#调用C/C++ DLL的相关说明
C# 调用DLL 常用如下方式来引用库中的函数 （当然还有很多其它的实现方式，这里就不多讲），本文主要讲要使用中遇到的常见问题:
一，库的引用 加上 ：using System.Runtime.InteropServices;
[DllImport("XXX")]
static extern void UbtServoGroupInit(ref UbtUartServo Sgroup, pwrite write, pread read);
上面有注意的有两点：
1，XXX 可以是DLL库名不带.dll 后辍，也可以是全名
2，函数前的 static extern 是一定要加的
二，DLL头文件实现
C#中没有.H文件，如果DLL中用到了一些头文件（里面有结构体等自定义类型），需在要C#环境中从新定义，这里会有各种变量的对应转换关系：
/****** 以下内容引自于https://www.cnblogs.com/zhaoxinshanwei/p/4008627.html ***********/
//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 ---- c#:StringBuilder
//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)]
//c++:char * ---- c#:string
//c++:char * ---- c#:StringBuilder
//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
/****** 以上内容引自于https://www.cnblogs.com/zhaoxinshanwei/p/4008627.html ***********/
根据上面的对应关系重新实现结构体或自定义类型，如：
public enum Status
{
Servo_OK = 0,
Servo_TimeOut,
Servo_ParErr,
Servo_LibInitErr,
Servo_TemperatureLow,
Servo_TemperatureHight,
Servo_VoltageLow,
Servo_VoltageHight,
Servo_CurrentOver,
Servo_TorqueOver,
Servo_FuseErr,
Servo_PwmErr,
Servo_CmdFail,
Servo_ReciveErr,
};
public struct UbtUartServo
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
string RxBuf;
//1.定义回调函数指针.
public pwrite write;
public pread read;
};
三，C#中如何实现类似于函数指针功能 （delegate）委托：
C/C++中的 typedef void (*pwrite)Byte buf, Byte size);
在C#可对应为：delegate void pwrite(ref Byte buf, Byte size);
如 在 C 中
typedef struct
{
uint8_t RxBuf[64];
void (*pwrite)(uint8_t *buf,uint8_t size) C51;
uint8_t (*pread)(uint8_t *buf,uint8_t size,uint8_t mstimeout) C51;
} UbtUartServo;
在C#的实现为：
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void pwrite(ref Byte buf, Byte size);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate Byte pread(ref Byte buf, Byte size, Byte mstimeout);
public struct UbtUartServo
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
string RxBuf;
//1.定义回调函数指针.
public pwrite write;
public pread read;
};
其中上面的，Cdecl说明DLL是C格式！
C++或其它可能要用不同的格式（前三个用的多一些，不过不行可以试度其它）：
namespace System.Runtime.InteropServices
{
[Serializable]
[ComVisible(true)]
public enum CallingConvention
{
Winapi = 1,
Cdecl = 2,
StdCall = 3,
ThisCall = 4,
FastCall = 5,
}
}
不然有可能会出现 如下错误：
The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void pwrite(ref Byte buf, Byte size);
四，给个例子：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace CshareServoTest
{
public enum Status
{
Servo_OK = 0,
Servo_TimeOut,
Servo_ParErr,
Servo_LibInitErr,
Servo_TemperatureLow,
Servo_TemperatureHight,
Servo_VoltageLow,
Servo_VoltageHight,
Servo_CurrentOver,
Servo_TorqueOver,
Servo_FuseErr,
Servo_PwmErr,
Servo_CmdFail,
Servo_ReciveErr,
};
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate void pwrite(ref Byte buf, Byte size);
[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
public delegate Byte pread(ref Byte buf, Byte size, Byte mstimeout);
public struct UbtUartServo
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
string RxBuf;
//1.定义回调函数指针.
public pwrite write;
public pread read;
};
public partial class Form1 : Form
{
[DllImport("ServoLibDll")]
static extern void UbtServoGroupInit(ref UbtUartServo Sgroup, pwrite write, pread read);
[DllImport("ServoLibDll")]
static extern Status UbtServoMove(ref UbtUartServo Sgroup, Byte ServoID, Byte TargetAngle, Int16 RunTime, UInt16 KeepTime, Byte BackTimeOut);
public UbtUartServo Test;
public Form1()
{
InitializeComponent();
Test = new UbtUartServo();
//Test.write = new pwrite(write);
//Test.read = new pread(read);
UbtServoGroupInit(ref Test, new pwrite(this.write), new pread(this.read));
}
private void TestButton_Click(object sender, EventArgs e)
{
UbtServoMove(ref Test, 0, 120, 25, 500, 50);
}
public void write(ref Byte buf, Byte size)
{
ServoTest.Text = "write";
return;
}
public Byte read(ref Byte buf, Byte size, Byte mstimeout)
{
ServoTest.Text = "read";
return 1;
}
}
}