這個我試了很多次,都沒成功。
最後我下載了別人的例子(工程)。
通過對比借鑑別人的寫法,很快就成功了。
最主要是這裏的寫法格式問題:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
namespace test_imp_dll
{
class CPPDLL
{
public enum my_enum { A, B, C };
const String str = @"D:\Files\test\testdll.dll";
[DllImport(str, EntryPoint = "add", SetLastError = true, CharSet = CharSet.Unicode, ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)]
public static extern int add(int a, int b);static void Main(string[] args)
{
Console.WriteLine("Hello World!\n");
int ret;
ret = CPPDLL.add(1, 2);
Console.WriteLine(ret);
}
}
}
然後我遇到了個很奇怪的問題
如果我拿C#的ref ulong,對照C++的unsigned long*,就運行正常
但我用C#的ulong對照C++的unsigned long就會出錯
我在網上找到下面這張C++與C#數據類型的對照表……上面明明寫着ulong是對應unsigned long的啊!?
可見也是人云亦云誤人子弟的玩意!
至於如何一勞永逸地解決C#參數類型與C++的對照問題,後面我會說。
參考(網上找到下面這張C++與C#數據類型的對照表,實際誤人子弟!):
https://blog.csdn.net/f_957995490/article/details/108066822
C#與C++數據類型對照表
//C++中的DLL函數原型爲
//extern “C” __declspec(dllexport) bool 方法名一(const char*
變量名1,unsigned char*
變量名2)
//extern “C” __declspec(dllexport) bool 方法名二(const unsigned char*
變量名1,char*
變量名2)
//C#調用C++的DLL蒐集整理的所有數據類型轉換方式,可能會有重複或者多種方案,自己多測試
//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
輸出變量名 ---- c#:StringBuilder
輸出變量名
//c++:LPCWSTR
---- c#:IntPtr
//c++:BOOL
---- c#:bool
//c++:HMODULE
---- c#:IntPtr
//c++:HINSTANCE
---- c#:IntPtr
//c++:結構體 ---- c#:public struct
結構體{};
//c++:結構體 **變量名 ---- c#:out
變量名 //C#中提前申明一個結構體實例化後的變量名
//c++:結構體 &變量名 ---- c#:ref
結構體 變量名
//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
變量名 ---- c#:byte
變量名
//c++:unsigned short
變量名 ---- c#:ushort
變量名
//c++:unsigned int
變量名 ---- c#:uint
變量名
//c++:unsigned long
變量名 ---- c#:ulong
變量名
//c++:char
變量名 ---- c#:byte
變量名 //C++中一個字符用一個字節表示,C#中一個字符用兩個字節表示
//c++:char
數組名[數組大小] ---- c#:MarshalAs(UnmanagedType.ByValTStr, SizeConst = 數組大小)] public string 數組名; ushort
//c++:char *
---- c#:string
//傳入參數
//c++:char *
---- c#:StringBuilder
//傳出參數
//c++:char *
變量名 ---- c#:ref string
變量名
//c++:char *
輸入變量名 ---- c#:string
輸入變量名
//c++:char *
輸出變量名 ---- c#:[MarshalAs(UnmanagedType.LPStr)] StringBuilder 輸出變量名
//c++:char**
---- c#:string
//c++:char **
變量名 ---- c#:ref string
變量名
//c++:const char *
---- c#:string
//c++:char[]
---- c#:string
//c++:char
變量名[數組大小] ---- c#:[MarshalAs(UnmanagedType.ByValTStr,SizeConst=數組大小)] public string 變量名;
//c++:struct
結構體名 *變量名 ---- c#:ref 結構體名 變量名
//c++:委託 變量名 ---- c#:委託 變量名
//c++:int
---- c#:int
//c++:int
---- c#:ref int
//c++:int &
---- c#:ref int
//c++:int *
---- c#:ref int
//C#中調用前需定義int 變量名 = 0;
//c++:*int
---- c#:IntPtr
//c++:int32 PIPTR *
---- c#:int32[]
//c++:float PIPTR *
---- c#:float[]
//c++:double**
數組名 ---- c#:ref double
數組名
//c++:double*[]
數組名 ---- c#:ref double
數組名
//c++:long
---- c#:int
//c++:ulong
---- c#:int
//c++:UINT8 *
---- c#:ref byte
//C#中調用前需定義byte 變量名 = 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 *
對象名稱 ---- c#:([MarshalAs(UnmanagedType.AsAny)]Object
對象名稱
//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#裏重新定義一個Struct
//CallBack回調函數需要封裝在一個委託裏,delegate static extern int FunCallBack(string str)
;
//unsigned char** ppImage
替換成IntPtr ppImage
//int& nWidth
替換成ref int nWidth
//int*
, int&
, 則都可用ref int
對應
//雙針指類型參數,可以用ref IntPtr
//函數指針使用c++: typedef double (*fun_type1)(double)
;對應 c#:public delegate double fun_type1(double)
;
//char*
的操作c++: char*
; 對應 c#:StringBuilder
;
//c#中使用指針:在需要使用指針的地方加unsafe
//unsigned char
對應public byte
上表就是在網上找的誤人子弟的玩意
接着說,我是怎麼徹底解決這個問題的
我用sizeof去求ulong的字節數,發現是8字節
然後用sizeof去求unsigned long的字節數,發現是4字節
C#使用ulong類型對應C++unsigned long類型出錯,可能是因爲字節長度不匹配,進而越界
而指針,之所以沒問題,大概因爲,不管什麼類型的指針,指針長度本身就是四字節。在調用時候,至少參數長度是一致的
爲了對應unsigned long四字節的長度,我選擇了C#的System.Int32作爲參數(四字節),就不會出錯了
下面是我的代碼,分別示範了C#對於帶有enum類型參數、char*類型參數、unsigned long和unsigned long*類型參數的C++函數的調用:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
namespace test_imp_dll
{
class CPPDLL
{
public enum my_enum { A, B, C };
const String str = @"D:\Files\test\testdll.dll";
[DllImport(str, EntryPoint = "add", SetLastError = true, CharSet = CharSet.Unicode, ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)]
public static extern int add(int a, int b);
[DllImport(str, EntryPoint = "get_str_len", SetLastError = true, CharSet = CharSet.Unicode, ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)]
public static extern int get_str_len(byte[] str);
[DllImport(str, EntryPoint = "test_enum", SetLastError = true, CharSet = CharSet.Unicode, ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)]
public extern static int test_enum(my_enum m);
[DllImport(str, EntryPoint = "test_unsigned_long_and_unsigned_long_ptr", SetLastError = true, CharSet = CharSet.Unicode, ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)]
public extern static int test_unsigned_long_and_unsigned_long_ptr(System.Int32 tmp_ulong, ref System.Int32 tmp_ulong_ptr);
static void Main(string[] args)
{
Console.WriteLine("Hello World!\n");
int ret;
ret = CPPDLL.add(1, 2);
Console.WriteLine("add返回值:" + ret);
Console.WriteLine("\n");
string tt = "hahaha";
byte[] ss = System.Text.Encoding.Default.GetBytes(tt);
ret = CPPDLL.get_str_len(ss);
Console.WriteLine("get_str_len返回值:" + ret);
Console.WriteLine("\n");
Console.Write("test_enum返回值:"+CPPDLL.test_enum(my_enum.C));
Console.WriteLine("\n");
Console.WriteLine("C#的System.Int32字節數爲(與C++ unsigned long的長度對應):" + sizeof(System.Int32));
Console.WriteLine("\n");
System.Int32 tmp2 = 2;
test_unsigned_long_and_unsigned_long_ptr(2,ref tmp2);
Console.WriteLine("test_unsigned_long_and_unsigned_long_ptr返回值:"+ tmp2);
Console.WriteLine("\n");
}
}
}
對應的C++庫函數的代碼:
#include "pch.h"
#include "test_dll.h"
int add(int a, int b)
{
return a + b;
}
int get_str_len(char* str)
{
return strlen(str);
}
int test_enum(my_enum m)
{
return (int)m;
}
int test_unsigned_long_and_unsigned_long_ptr(unsigned long tmp_ulong, unsigned long* tmp_ulong_ptr)
{
if (tmp_ulong == 1)
*tmp_ulong_ptr = 1;
else
*tmp_ulong_ptr = 2;
return 0;
}
我也將我的demo上傳到了github:
https://github.com/SonnAdolf/test_csharp_imp_cplusplus_dll
問題的關鍵是,一定要讓參數的數據類型長度對應……