Mapping type between C++ and C#

API Data Type	Type Description	C# Type	API Data Type	Type Description	C# Type
WORD	16 bit unsigned int	ushort	CHAR	char	char
LONG	32 bit unsigned int	int	DWORDLONG	64 bit long int	long
DWORD	32 bit unsigned int	uint	HDC	Device decription table handle	int
HANDLE	handle,32 bit int	int	HGDIOBJ	GDI object handle	int
UINT	32 bit unsigned int	uint	HINSTANCE	Instance handle	int
BOOL	32bit bool	bool	HWM	Window handle	int
LPSTR	32-bit pointer pointing to the character	string	HPARAM	32 bit message parameters	int
LPCSTR	32-bit pointer pointing to the const character	String	LPARAM	32 bit message parameters	int
BYTE	byte	byte	WPARAM	32 bit message parameters	int

Unmanaged Types in Wtypes.h	Unmanaged C Types	Managed class name	Comment
HANDLE	void*	System.IntPtr	32 bit
BYTE	unsigned char	System.Byte	8 bit
SHORT	short	System.Int16	16 bit
WORD	unsigned short	System.UInt16	16 bit
INT	int	System.Int32	32 bit
UINT	unsigned int	System.UInt32	32 bit
LONG	long	System.Int32	32 bit
BOOL	long	System.Int32	32 bit
DWORD	unsigned long	System.UInt32	32 位
ULONG	unsigned long	System.UInt32	32 位
CHAR	char	System.Char	use ANSI
LPSTR	char*	System.String 或 System.StringBuilder	use ANSI
LPCSTR	Const char*	System.String 或 System.StringBuilder	use ANSI
LPWSTR	wchar_t*	System.String 或 System.StringBuilder	use Unicode
LPCWSTR	Const wchar_t*	System.String 或 System.StringBuilder	use Unicode
FLOAT	Float	System.Single	32 bit
DOUBLE	Double	System.Double	64 bit

Types map to System namespace in C++
BOOL=System.Int32	HGDIOBJ=System.IntPtr	LONG32=System.Int32	PCHAR=System.Char[]	PWORD=System.Int16[]
BOOLEAN=System.Int32	HGLOBAL=System.IntPtr	LONG64=System.Int64	PCSTR=System.String	PWSTR=System.String
BYTE=System.UInt16	HHOOK=System.IntPtr	LONGLONG=System.Int64	PCTSTR=System.String	REGSAM=System.UInt32
CHAR=System.Int16	HICON=System.IntPtr	LPARAM=System.IntPtr	PCWCH=System.UInt32	SC_HANDLE=System.IntPtr
COLORREF=System.UInt32	HIMAGELIST=System.IntPtr	LPBOOL=System.Int16[]	PCWSTR=System.UInt32	SC_LOCK=System.IntPtr
DWORD=System.UInt32	HIMC=System.IntPtr	LPBYTE=System.UInt16[]	PDWORD=System.Int32[]	SHORT=System.Int16
DWORD32=System.UInt32	HINSTANCE=System.IntPtr	LPCOLORREF=System.UInt32[]	PFLOAT=System.Float[]	SIZE_T=System.UInt32
DWORD64=System.UInt64	HKEY=System.IntPtr	LPCSTR=System.String	PHANDLE=System.UInt32	SSIZE_=System.UInt32
FLOAT=System.Float	HLOCAL=System.IntPtr	LPCTSTR=System.String	PHKEY=System.UInt32	TBYTE=System.Char
HACCEL=System.IntPtr	HMENU=System.IntPtr	LPCVOID=System.UInt32	PINT=System.Int32[]	TCHAR=System.Char
HANDLE=System.IntPtr	HMETAFILE=System.IntPtr	LPCWSTR=System.String	PLCID=System.UInt32	UCHAR=System.Byte
HBITMAP=System.IntPtr	HMODULE=System.IntPtr	LPDWORD=System.UInt32[]	PLONG=System.Int32[]	UINT=System.UInt32
HBRUSH=System.IntPtr	HMONITOR=System.IntPtr	LPHANDLE=System.UInt32	PLUID=System.UInt32	UINT32=System.UInt32
HCONV=System.IntPtr	HPALETTE=System.IntPtr	LPINT=System.Int32[]	PSHORT=System.Int16[]	UINT64=System.UInt64
HCONVLIST=System.IntPtr	HPEN=System.IntPtr	LPLONG=System.Int32[]	PSTR=System.String	ULONG=System.UInt32
HCURSOR=System.IntPtr	HRGN=System.IntPtr	LPSTR=System.String	PTBYTE=System.Char[]	ULONG32=System.UInt32
HDC=System.IntPtr	HRSRC=System.IntPtr	LPTSTR=System.String	PTCHAR=System.Char[]	ULONG64=System.UInt64
HDDEDATA=System.IntPtr	HSZ=System.IntPtr	LPVOID=System.UInt32	PTSTR=System.String	ULONGLONG=System.UInt64
HDESK=System.IntPtr	HWINSTA=System.IntPtr	LPWORD=System.Int32[]	PUCHAR=System.Char[]	USHORT=System.UInt16
HDROP=System.IntPtr	HWND=System.IntPtr	LPWSTR=System.String	PUINT=System.UInt32[]	WORD=System.UInt16
HDWP=System.IntPtr	INT=System.Int32	LRESULT=System.IntPtr	PULONG=System.UInt32[]	WPARAM=System.IntPtr
HENHMETAFILE=System.IntPtr	INT32=System.Int32	PBOOL=System.Int16[]	PUSHORT=System.UInt16[]
HFILE=System.IntPtr	INT64=System.Int64	PBOOLEAN=System.Int16[]	PVOID=System.UInt32
HFONT=System.IntPtr	LONG=System.Int32	PBYTE=System.UInt16[]	PWCHAR=System.Char[]

An example:

C# Method	IDL Equivalent	Calling semantics in C#
public void Method(String strInput);	HRESULT Method([in] BSTR strInput);	obj.Method("Hello There");
public String Method();	HRESULT Method([out, retval] BSTR* pRetVal);	String strOutput = obj.Method();
public String Method(ref String strPassAndModify);	HRESULT Method([in, out] BSTR* strPassAndModify, [out, retval] BSTR* pRetVal);	String strHello = "Hello There"; String strOutput = obj.Method(ref strHello);
public String Method(out String strReturn);	HRESULT Method([out] BSTR* strReturn, [out, retval] BSTR* pRetVal);	//Need not initialize strHello String strHello; String strOutput = obj.Method(out strHello);
public String Method(String strFirst, out String strSecond, ref String strThird);	HRESULT Method([in] BSTR bstrFirst, [out] BSTR* strSecond, [in, out] BSTR* strThird, [out, retval] BSTR* pRetVal);	String strFirst = "Hi There"; String strSecond; String strThird = "Hello World"; String strOutput = obj.Method(strFirst,out strSecond, ref strThird);

COM Data Types From Microsoft

Pasted from <http://msdn.microsoft.com/en-us/library/sak564ww(v=VS.71).aspx>

COM value type	COM reference type	System type
bool	bool *	System.Int32
char, small	char *, small *	System.SByte
short	short *	System.Int16
long, int	long *, int *	System.Int32
Hyper	hyper *	System.Int64
unsigned char, byte	unsigned char *, byte *	System.Byte
wchar_t, unsigned short	wchar_t *, unsigned short *	System.UInt16
unsigned long, unsigned int	unsigned long *, unsigned int *	System.UInt32
unsigned hyper	unsigned hyper *	System.UInt64
float	float *	System.Single
double	double *	System.Double
VARIANT_BOOL	VARIANT_BOOL *	System.Boolean
void *	void **	System.IntPtr
HRESULT	HRESULT *	System.Int16 or System.IntPtr
SCODE	SCODE *	System.Int32
BSTR	BSTR *	System.String
LPSTR or [string, ...] char *	LPSTR *	System.String
LPWSTR or [string, ...] wchar_t *	LPWSTR *	System.String
VARIANT	VARIANT *	System.Object
DECIMAL	DECIMAL *	System.Decimal
DATE	DATE *	System.DateTime
GUID	GUID *	System.Guid
CURRENCY	CURRENCY *	System.Decimal
IUnknown *	IUnknown **	System.Object
IDispatch *	IDispatch **	System.Object
SAFEARRAY(type)	SAFEARRAY(type) *	type[]

The following table lists COM value and reference types that convert to corresponding element types. For example, a COM coclass automatically maps to a managed class with the same name.

COM value type	COM reference type	Element type
typedef BaseType MyType	ByRef BaseType	BaseType
MyStruct	ByRef VALUETYPE<MyStruct>	valuetype<MyStruct>
MyEnum	ByRef VALUETYPE<MyEnum>	valuetype<MyEnum>
MyInterface *	ByRef CLASS <MyInterface>	Class <MyInterface>
MyCoClass	ByRef CLASS <_Class>	class <_Class>

Pasted from <http://msdn.microsoft.com/en-us/library/sak564ww(v=VS.71).aspx>