1.5w+
社区成员
- 主页
- VC综合技术
- 互联网技术
- MFC AppLauncher
- .NET 技术
- 界面
- 进程
- 算法
- 硬件/系统
- 数据库
- VC++技术资源
关于File Mapping 的问题
在CreateFileMapping((HANDLE)0xFFFFFFFF, NULL, PAGE_READWRITE, 0, MAX_CHANNEL_PKTS*42+64, "GxReceiv")里(HANDLE)0xFFFFFFFF是什么意思？
为什么要这么表示？
为什么要这么表示？
...全文
请发表友善的回复…
发表回复
likebj 2002-07-23
麻烦
likebj 2002-07-23
我知道了，可是MFC里是这样的：
#define INVALID_HANDLE_VALUE (HANDLE)-1
怎么会是0xFFFFFFFF呢？
#define INVALID_HANDLE_VALUE (HANDLE)-1
怎么会是0xFFFFFFFF呢？
FallingAngle 2002-07-23
(HANDLE)0xFFFFFFFF就是INVALID_HANDLE_VALUE
MSDN:
hFile
[in] Handle to the file from which to create a mapping object. The file must be opened with an access mode compatible with the protection flags specified by the flProtect parameter. It is recommended, though not required, that files you intend to map be opened for exclusive access.
If hFile is INVALID_HANDLE_VALUE, the calling process must also specify a mapping object size in the dwMaximumSizeHigh and dwMaximumSizeLow parameters. In this case, CreateFileMapping creates a file-mapping object of the specified size backed by the operating-system paging file rather than by a named file in the file system. The file-mapping object can be shared through duplication, through inheritance, or by name. The initial contents of the pages in the file-mapping object are zero.
MSDN:
hFile
[in] Handle to the file from which to create a mapping object. The file must be opened with an access mode compatible with the protection flags specified by the flProtect parameter. It is recommended, though not required, that files you intend to map be opened for exclusive access.
If hFile is INVALID_HANDLE_VALUE, the calling process must also specify a mapping object size in the dwMaximumSizeHigh and dwMaximumSizeLow parameters. In this case, CreateFileMapping creates a file-mapping object of the specified size backed by the operating-system paging file rather than by a named file in the file system. The file-mapping object can be shared through duplication, through inheritance, or by name. The initial contents of the pages in the file-mapping object are zero.
likebj 2002-07-23
这样啊，知道了！：）我怎么给你们加不了分？
yonghengdizhen 2002-07-23
我知道了，可是MFC里是这样的：
#define INVALID_HANDLE_VALUE (HANDLE)-1
怎么会是0xFFFFFFFF呢
-1的十六进制表示就是0xFFFFFFFF
DWORD
#define INVALID_HANDLE_VALUE (HANDLE)-1
怎么会是0xFFFFFFFF呢
-1的十六进制表示就是0xFFFFFFFF
DWORD
SoftAngel 2002-07-23
使用(HANDLE)0xFFFFFFFF做参数，是说并不是真的要映射文件，而是创建一共享内存块，在使用mapviewoffile后，可以使用这块共享内存，这是进程间通讯最常用的一种方法。
ivefire 2002-07-23
#define HANDLE 0
#define INVALID_HANDLE_VALUE (HANDLE)-1
INVALID_HANDLE_VALUE 就是0xFFFFFFFF
在CreateFileMapping((HANDLE)0xFFFFFFFF, NULL, PAGE_READWRITE, 0, MAX_CHANNEL_PKTS*42+64, "GxReceiv")中(HANDLE)0xFFFFFFFF表示在系统的页文件里建立FileMapping
#define INVALID_HANDLE_VALUE (HANDLE)-1
INVALID_HANDLE_VALUE 就是0xFFFFFFFF
在CreateFileMapping((HANDLE)0xFFFFFFFF, NULL, PAGE_READWRITE, 0, MAX_CHANNEL_PKTS*42+64, "GxReceiv")中(HANDLE)0xFFFFFFFF表示在系统的页文件里建立FileMapping