最近初学这个东西，看MSDN上说
DWORD GetFileSize(
HANDLE hFile,
LPDWORD lpFileSizeHigh
);
第二个参数是高位，返回值是低位，还有各种GetLastError的处理：
（原文）：Return Values
The low-order DWORD of the file size indicates success. If lpFileSizeHigh is not NULL, the function puts the high-order DWORD of the file size into the variable pointed to by that parameter. If lpFileSizeHigh is NULL, 0xFFFFFFFF indicates failure. To get extended error information, call GetLastError. If lpFileSizeHigh is not NULL, 0xFFFFFFFF indicates failure and GetLastError returns a value other than NO_ERROR. Res
If the return value is 0xFFFFFFFF and lpFileSizeHigh is not NULL, an application must call GetLastError to determine whether the function has succeeded or failed. The following code sample shows this point.
看的头晕，请问哪个大侠能给个使用该函数的安全的代码处理，就是要怎么用才是比较安全的
DWORD GetFileSize(
HANDLE hFile,
LPDWORD lpFileSizeHigh
);
第二个参数是高位，返回值是低位，还有各种GetLastError的处理：
（原文）：Return Values
The low-order DWORD of the file size indicates success. If lpFileSizeHigh is not NULL, the function puts the high-order DWORD of the file size into the variable pointed to by that parameter. If lpFileSizeHigh is NULL, 0xFFFFFFFF indicates failure. To get extended error information, call GetLastError. If lpFileSizeHigh is not NULL, 0xFFFFFFFF indicates failure and GetLastError returns a value other than NO_ERROR. Res
If the return value is 0xFFFFFFFF and lpFileSizeHigh is not NULL, an application must call GetLastError to determine whether the function has succeeded or failed. The following code sample shows this point.
看的头晕，请问哪个大侠能给个使用该函数的安全的代码处理，就是要怎么用才是比较安全的
主要分 两种情况， lpFileSizeHigh == NULL or not NULL
情况1 lpFileSizeHigh == NULL
if(GetFileSize(hFile,NULL) == 0xFFFFFFFF )
{
TRACE("call fail\n");
}
else
{
TRACE("call succ\n");
}
情况2 lpFileSizeHigh !=NULL
if(GetFileSize(hFile,&iFileSizeHigh) == 0xFFFFFFFF )
{
iErr =GetLastError();
if(iError ==0)
{
TRACE("call succ\n");
}
else
{
TRACE("call fail\n");
}}
else
{
TRACE("call succ\n");
}简单的写了一下啊，你可以自己封一个安全函数
/*
This program demonstrates file mapping, especially how to align a
view with the system file allocation granularity.
*/#include <windows.h>
#include <stdio.h>#define BUFFSIZE 1024 // size of the memory to examine at any one time#define FILE_MAP_START 138240 // starting point within the file of
// the data to examine (135K)/* The test file. The code below creates the file and populates it,
so there is no need to supply it in advance. */TCHAR * lpcTheFile = TEXT("fmtest.txt"); // the file to be manipulatedint main(void)
{
HANDLE hMapFile; // handle for the file's memory-mapped region
HANDLE hFile; // the file handle
BOOL bFlag; // a result holder
DWORD dBytesWritten; // number of bytes written
DWORD dwFileSize; // temporary storage for file sizes
DWORD dwFileMapSize; // size of the file mapping
DWORD dwMapViewSize; // the size of the view
DWORD dwFileMapStart; // where to start the file map view
DWORD dwSysGran; // system allocation granularity
SYSTEM_INFO SysInfo; // system information; used to get granularity
LPVOID lpMapAddress; // pointer to the base address of the
// memory-mapped region
char * pData; // pointer to the data
int i; // loop counter
int iData; // on success contains the first int of data
int iViewDelta; // the offset into the view where the data
//shows up // Create the test file. Open it "Create Always" to overwrite any
// existing file. The data is re-created below
hFile = CreateFile(lpcTheFile,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
NULL); if (hFile == INVALID_HANDLE_VALUE)
{
printf("hFile is NULL\n");
printf("Target file is %s\n",
lpcTheFile);
return 4;
} // Get the system allocation granularity.
GetSystemInfo(&SysInfo);
dwSysGran = SysInfo.dwAllocationGranularity; // Now calculate a few variables. Calculate the file offsets as
// 64-bit values, and then get the low-order 32 bits for the
// function calls. // To calculate where to start the file mapping, round down the
// offset of the data into the file to the nearest multiple of the
// system allocation granularity.
dwFileMapStart = (FILE_MAP_START / dwSysGran) * dwSysGran;
printf ("The file map view starts at %ld bytes into the file.\n",
dwFileMapStart); // Calculate the size of the file mapping view.
dwMapViewSize = (FILE_MAP_START % dwSysGran) + BUFFSIZE;
printf ("The file map view is %ld bytes large.\n",
dwMapViewSize); // How large will the file mapping object be?
dwFileMapSize = FILE_MAP_START + BUFFSIZE;
printf ("The file mapping object is %ld bytes large.\n",
dwFileMapSize); // The data of interest isn't at the beginning of the
// view, so determine how far into the view to set the pointer.
iViewDelta = FILE_MAP_START - dwFileMapStart;
printf ("The data is %d bytes into the view.\n",
iViewDelta); // Now write a file with data suitable for experimentation. This
// provides unique int (4-byte) offsets in the file for easy visual
// inspection. Note that this code does not check for storage
// medium overflow or other errors, which production code should
// do. Because an int is 4 bytes, the value at the pointer to the
// data should be one quarter of the desired offset into the file for (i=0; i<(int)dwSysGran; i++)
{
WriteFile (hFile, &i, sizeof (i), &dBytesWritten, NULL);
} // Verify that the correct file size was written.
dwFileSize = GetFileSize(hFile, NULL);
printf("hFile size: %10d\n", dwFileSize); // Create a file mapping object for the file
// Note that it is a good idea to ensure the file size is not zero
hMapFile = CreateFileMapping( hFile, // current file handle
NULL, // default security
PAGE_READWRITE, // read/write permission
0, // size of mapping object, high
dwFileMapSize, // size of mapping object, low
NULL); // name of mapping object if (hMapFile == NULL)
{
printf("hMapFile is NULL: last error: %d\n", GetLastError() );
return (2);
} // Map the view and test the results. lpMapAddress = MapViewOfFile(hMapFile, // handle to
// mapping object
FILE_MAP_ALL_ACCESS, // read/write
0, // high-order 32
// bits of file
// offset
dwFileMapStart, // low-order 32
// bits of file
// offset
dwMapViewSize); // number of bytes
// to map
if (lpMapAddress == NULL)
{
printf("lpMapAddress is NULL: last error: %d\n", GetLastError());
return 3;
} // Calculate the pointer to the data.
pData = (char *) lpMapAddress + iViewDelta; // Extract the data, an int. Cast the pointer pData from a "pointer
// to char" to a "pointer to int" to get the whole thing
iData = *(int *)pData; printf ("The value at the pointer is %d,\n"
"which %s one quarter of the desired file offset.\n",
iData,
iData*4 == FILE_MAP_START ? "is" : "is not"); // Close the file mapping object and the open file bFlag = UnmapViewOfFile(lpMapAddress);
bFlag = CloseHandle(hMapFile); if(!bFlag)
{
printf("\nError %ld occurred closing the mapping object!",
GetLastError());
} bFlag = CloseHandle(hFile); if(!bFlag)
{
printf("\nError %ld occurred closing the file!",
GetLastError());
} return 0;
}