黄森堂(vcmfc)
1.FALSE/TRUE与false/true的区别:
false/true是标准C++语言里新增的关键字,而FALSE/TRUE是通过#define,这要用途是解决程序在C与C++中环境的差异,以下是FALSE/TRUE在windef.h的定义:
#ifndef FALSE#define FALSE 0#endif#ifndef TRUE#define TRUE 1#endif
也就是说FALSE/TRUE是int类型,而false/true是bool类型;所以两者不一样的,只不过我们在使用中没有这种感觉,因为C++会帮你做隐式转换。
2.bool的大小与BOOL的区别:
bool在C++里是占用1字节,而BOOL是int类型,int类型的大小是视具体环境而定的;所以来说:false/true只占用1个字节,而TRUE/FALSE视具体环境而言,以下是BOOL在windef.h中的定义:typedef int BOOL;
3.NULL与0的区别:
还是让我们看一下windef.h中NULL的定义:
#ifndef NULL#ifdef __cplusplus//这个是指示是用C++来编译程序#define NULL 0#else#define NULL ((void *)0)#endif#endif
所以说:它们没有区别,只不过在C里面会做一个强制类型转换。
4.HINSTANCE与HMODULE的区别:
在windef.h中的定义:
typedef HINSTANCE HMODULE; /* HMODULEs can be used in place of HINSTANCEs */
5.CALLBACK,WINAPI的实质:
在windef.h中的定义:
#undef far#undef near#undef pascal#define far#define near#if (!defined(_MAC)) && ((_MSC_VER >= 800) || defined(_STDCALL_SUPPORTED)) #define pascal __stdcall#else #define pascal#endif#if defined(DOSWIN32) || defined(_MAC) #define cdecl _cdecl #ifndef CDECL #define CDECL _cdecl #endif#else #define cdecl #ifndef CDECL #define CDECL #endif#endif#ifdef _MAC #define CALLBACK PASCAL #define WINAPI CDECL #define WINAPIV CDECL #define APIENTRY WINAPI #define APIPRIVATE CDECL #ifdef _68K_ #define PASCAL __pascal #else #define PASCAL #endif#elif (_MSC_VER >= 800) || defined(_STDCALL_SUPPORTED) #define CALLBACK __stdcall #define WINAPI __stdcall #define WINAPIV __cdecl #define APIENTRY WINAPI #define APIPRIVATE __stdcall #define PASCAL __stdcall #else #define CALLBACK #define WINAPI #define WINAPIV #define APIENTRY WINAPI #define APIPRIVATE #define PASCAL pascal#endif
6.一些常见类型的定义:
在windef.h中的定义:
typedef UINT WPARAM;typedef LONG LPARAM;typedef LONG LRESULT;
typedef int INT;typedef unsigned int UINT;
typedef unsigned long DWORD;typedef int BOOL;typedef unsigned char BYTE;typedef unsigned short WORD;typedef float FLOAT;
typedef unsigned long ULONG;typedef unsigned short USHORT;typedef unsigned char UCHAR;typedef char *PSZ;
7.常见Window资源类型的实质:
在windef.h中的定义:
DECLARE_HANDLE(HPEN);DECLARE_HANDLE(HBITMAP);DECLARE_HANDLE(HBRUSH);DECLARE_HANDLE(HDC);DECLARE_HANDLE(HFONT);DECLARE_HANDLE(HICON);DECLARE_HANDLE(HMENU);DECLARE_HANDLE(HMETAFILE);DECLARE_HANDLE(HINSTANCE);DECLARE_HANDLE(HPALETTE);typedef WORD ATOM;typedef HANDLE HGLOBAL;typedef HANDLE HLOCAL;typedef HANDLE GLOBALHANDLE;typedef HANDLE LOCALHANDLE;typedef HICON HCURSOR; /* HICONs & HCURSORs are polymorphic */typedef DWORD COLORREF;
在windowsx.h中:
#define DECLARE_HANDLE32 DECLARE_HANDLE
penwin.h:
#ifndef DECLARE_HANDLE32#define DECLARE_HANDLE32(name)/struct name##__ { int unused; };/typedef const struct name##__ FAR* name#endif //!DECLARE_HANDLE32
6.PlatForm的编译版本的相关预处理宏:
MacroDescription__cplusplusDefined for C++ programs only._MFC_VERDefines the MFC version. Defined as 0x0421 for Microsoft Foundation Class Library 4.21. Always defined._MSC_VERDefines the compiler version. Defined as 1200 for Microsoft Visual C++ 6.0. Always defined._WIN32Defined for applications for Win32®. Always defined