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VC++中的数据类型

楼主sunjet2000（小菜）2003-12-02 08:09:48 在 VC/MFC / 基础类提问

我在一些程序中看到把内存偏移量用DWORD来表示，用int不行吗？我觉得DWORD总是怪怪的不是很熟悉。用他有什么好处吗？还有在图形的坐标了，图形的范围了。我看到有的程序用double,有的用float类型，我应该用什么类型比较好呢？如果我在一个程序里都用了这两个类型，在类型转换的过程中应该注意什么呢？会不会是数据丢失呢？还有呀，别闲我烦哦。。。还有您看有好多程序里都用了LPVOID、LPCTSTR 这些个指针，您说这些指针比平常的指针有什么好处吗？大家踊跃发言呀！为了中国的崛起而回帖！！！问题点数：100、回复次数：13Top

1 楼wyz_csdn（网语者）回复于 2003-12-02 08:33:15 得分 0

这些都是VC里定义的宏。看MSDN帮助就行了Top

2 楼mfc168（子非鱼）回复于 2003-12-02 08:41:08 得分 0

DWORD是无符号的32位的整型，int为16位

float为 4字节，表示范围 3.4E +/- 38 (7 digits)
double 为8字节表示范围 1.7E +/- 308 (15 digits)
最好用double，转换过程中，在从double转为float的时候会出现数据丢失，反之不会

LPVOID、LPCTSTR 都是长指针，为32位Top

3 楼nkwesley（江南丝竹）回复于 2003-12-02 08:41:09 得分 0

对，多研究MSDN好处多多啊
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4 楼sxslyy（孤松傲雪）回复于 2003-12-02 08:57:35 得分 0

markTop

5 楼sxslyy（孤松傲雪）回复于 2003-12-02 09:01:50 得分 0

mfc168(闶阆——项目开发中) ( ) :
我认为VC中int是有符号32位(4字节)
没有什么长指针,指针都是4个字节32位长.
可以用sizeof(int),sizeof(LPSTR)看看
你记错了吧!Top

6 楼sunjet2000（小菜）回复于 2003-12-02 09:08:12 得分 0

mfc168(闶阆——项目开发中) 您给我这些变量的单位我也知道呀。但是这些变量的单位和选择这个变量有什么关系呢？还有您说：LPVOID、LPCTSTR 都是长指针，为32位。这我也知道，但是为什么不用短指针而用长指针呢？我是问为什么用他。
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7 楼greensofter（MC.CN）回复于 2003-12-02 09:33:51 得分 0

int是有符号32位（在32位系统中），DWORD是无符号32位。用32位的指针寻址范围更大。Top

8 楼iicup（双杯献酒）回复于 2003-12-02 09:34:24 得分 60

DWORD 永远是32位
int 可能是32位，也可能是16位，
视机器编译器和编译选项而定。
将来是64位也有可能。
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9 楼derryzhang（雨田）回复于 2003-12-02 10:35:54 得分 0

Right!~~Top

10 楼xiaodongliu（阿东）回复于 2003-12-02 10:36:27 得分 0

msdn或者多看看vc++技术内幕Top

11 楼farfh（阿远之哈儿）回复于 2003-12-02 11:27:35 得分 30

反正在现在的机子上，一律认为int long dword 的长度都32一般都没错的。呵呵，区别可以认为不存在。不过为了代码以后的可扩展性和兼容性，建议还是用DWORD，保险:)Top

12 楼ISunwu（刀口蒙特）回复于 2003-12-02 11:35:16 得分 0

MS这么用自然有它的道理。大家都遵循这个规则，就可以了。
谁叫我们是在他的基础上编码呢？Top

13 楼seilfer2000（郁闷，疯狂学习中）回复于 2003-12-02 11:48:55 得分 10

Data Types
Value Meaning
ATOM Atom. For more information, see Atoms.
BOOL Boolean variable (should be TRUE or FALSE).
BOOLEAN Boolean variable (should be TRUE or FALSE).
BYTE Byte (8 bits).
CALLBACK Calling convention for callback functions.
CHAR 8-bit Windows (ANSI) character. For more information, see Character Sets Used By Fonts.
COLORREF Red, green, blue (RGB) color value (32 bits). See COLORREF for information on this type.
CONST Variable whose value is to remain constant during execution.
CRITICAL_SECTION Critical-section object. For more information, see Critical Section Objects.
DWORD 32-bit unsigned integer.
DWORD_PTR Unsigned long type for pointer precision. Use when casting a pointer to a long type to perform pointer arithmetic. (Also commonly used for general 32-bit parameters that have been extended to 64 bits in 64-bit Windows. )
DWORD32 32-bit unsigned integer.
DWORD64 64-bit unsigned integer.
FLOAT Floating-point variable.
HACCEL Handle to an accelerator table.
HANDLE Handle to an object.
HBITMAP Handle to a bitmap.
HBRUSH Handle to a brush.
HCONV Handle to a dynamic data exchange (DDE) conversation.
HCONVLIST Handle to a DDE conversation list.
HCURSOR Handle to a cursor.
HDC Handle to a device context (DC).
HDDEDATA Handle to DDE data.
HDESK Handle to a desktop.
HDROP Handle to an internal drop structure.
HDWP Handle to a deferred window position structure.
HENHMETAFILE Handle to an enhanced metafile.
HFILE Handle to a file opened by OpenFile, not CreateFile.
HFONT Handle to a font.
HGDIOBJ Handle to a GDI object.
HGLOBAL Handle to a global memory block.
HHOOK Handle to a hook.
HICON Handle to an icon.
HIMAGELIST Handle to an image list.
HIMC Handle to input context.
HINSTANCE Handle to an instance.
HKEY Handle to a registry key.
HKL Input locale identifier.
HLOCAL Handle to a local memory block.
HMENU Handle to a menu.
HMETAFILE Handle to a metafile.
HMODULE Handle to a module. The value is the base address of the module.
HMONITOR Handle to a display monitor.
HPALETTE Handle to a palette.
HPEN Handle to a pen.
HRGN Handle to a region.
HRSRC Handle to a resource.
HSZ Handle to a DDE string.
HWINSTA Handle to a window station.
HWND Handle to a window.
INT 32-bit signed integer.
INT_PTR Signed integral type for pointer precision. Use when casting a pointer to an integer to perform pointer arithmetic.
INT32 32-bit signed integer.
INT64 64-bit signed integer.
LANGID Language identifier. For more information, see Locales.
LCID Locale identifier. For more information, see Locales.
LCTYPE Locale information type. For a list, see Locale and Language Information.
LONG 32-bit signed integer.
LONG_PTR Signed long type for pointer precision. Use when casting a pointer to a long to perform pointer arithmetic.
LONG32 32-bit signed integer.
LONG64 64-bit signed integer.
LONGLONG 64-bit signed integer.
LPARAM Message parameter.
LPBOOL Pointer to a BOOL.
LPBYTE Pointer to a BYTE.
LPCOLORREF Pointer to a COLORREF value.
LPCRITICAL_SECTION Pointer to a CRITICAL_SECTION.
LPCSTR Pointer to a constant null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.
LPCTSTR An LPCWSTR if UNICODE is defined, an LPCTSTR otherwise.
LPCVOID Pointer to a constant of any type.
LPCWSTR Pointer to a constant null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.
LPDWORD Pointer to a DWORD.
LPHANDLE Pointer to a HANDLE.
LPINT Pointer to an INT.
LPLONG Pointer to a LONG.
LPSTR Pointer to a null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.
LPTSTR An LPWSTR if UNICODE is defined, an LPSTR otherwise.
LPVOID Pointer to any type.
LPWORD Pointer to a WORD.
LPWSTR Pointer to a null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.
LRESULT Signed result of message processing.
LUID Locally unique identifier.
PBOOL Pointer to a BOOL.
PBOOLEAN Pointer to a BOOL.
PBYTE Pointer to a BYTE.
PCHAR Pointer to a CHAR.
PCRITICAL_SECTION Pointer to a CRITICAL_SECTION.
PCSTR Pointer to a constant null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.
PCTSTR A PCWSTR if UNICODE is defined, a PCSTR otherwise.
PCWCH Pointer to a constant WCHAR.
PCWSTR Pointer to a constant null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.
PDWORD Pointer to a DWORD.
PFLOAT Pointer to a FLOAT.
PHANDLE Pointer to a HANDLE.
PHKEY Pointer to an HKEY.
PINT Pointer to an INT.
PLCID Pointer to an LCID.
PLONG Pointer to a LONG.
PLUID Pointer to a LUID.
POINTER_32 32-bit pointer. On a 32-bit system, this is a native pointer. On a 64-bit system, this is a truncated 64-bit pointer.
POINTER_64 64-bit pointer. On a 64-bit system, this is a native pointer. On a 32-bit system, this is a sign-extended 32-bit pointer.
PSHORT Pointer to a SHORT.
PSTR Pointer to a null-terminated string of 8-bit Windows (ANSI) characters. For more information, see Character Sets Used By Fonts.
PTBYTE Pointer to a TBYTE.
PTCHAR Pointer to a TCHAR.
PTSTR PWSTR if UNICODE is defined, a PSTR otherwise.
PTBYTE Pointer to a TBYTE.
PTCHAR Pointer to a TCHAR.
PTSTR A PWSTR if UNICODE is defined, a PSTR otherwise.
PUCHAR Pointer to a UCHAR.
PUINT Pointer to a UINT.
PULONG Pointer to a ULONG.
PUSHORT Pointer to a USHORT.
PVOID Pointer to any type.
PWCHAR Pointer to a WCHAR.
PWORD Pointer to a WORD.
PWSTR Pointer to a null-terminated string of 16-bit Unicode characters. For more information, see Character Sets Used By Fonts.
REGSAM Security access mask for registry key.
SC_HANDLE Handle to a service control manager database. For more information, see SCM Handles.
SC_LOCK Handle to a service control manager database lock. For more information, see SCM Handles.
SERVICE_STATUS_HANDLE Handle to a service status value. For more information, see SCM Handles.
SHORT Short integer (16 bits).
SIZE_T The maximum number of bytes to which a pointer can point. Use for a count that must span the full range of a pointer.
SSIZE_ T Signed SIZE_T.
TBYTE A WCHAR if UNICODE is defined, a CHAR otherwise.
TCHAR A WCHAR if UNICODE is defined, a CHAR otherwise.
UCHAR Unsigned CHAR.
UINT Unsigned INT.
UINT_PTR Unsigned INT_PTR.
UINT32 Unsigned INT32.
UINT64 Unsigned INT64.
ULONG Unsigned LONG.
ULONG_PTR Unsigned LONG_PTR.
ULONG32 Unsigned LONG32.
ULONG64 Unsigned LONG64.
ULONGLONG 64-bit unsigned integer.
UNSIGNED Unsigned attribute.
USHORT Unsigned SHORT.
VOID Any type.
WCHAR 16-bit Unicode character. For more information, see Character Sets Used By Fonts.
WINAPI Calling convention for system functions.
WORD 16-bit unsigned integer.
WPARAM Message parameter.

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DWORD 32-bit unsigned integer.
INT 32-bit signed integer.
上面是所有的类型看看就知道区别了
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