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发表于 2018-12-9 19:12
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的确如是，先弄清楚，数组都能装什么后，再充分利用数组的特性提高效率与优化代码……
CSDN上看到一篇文章，使用内存映射文件的步骤：
1、创建或打开一个文件内核对象，该对象标识了我们想要用作内存映射文件的那个磁盘文件。
CreateFile();
2、创建一个文件映射内核对象，来告诉系统文件的大小以及我们打算如何访问文件。
CreateFileMapping();
3、告诉系统把文件映射对象的部分或全部映射到进程的地址空间中。
MapViewOfFile();
用完内存映射文件之后，必须执行以下三步进行清理。
1、告诉系统从进程地址空间中取消对文件映射内核对象的映射。
UnmapViewOfFile();
2、关闭文件映射内核对象。
CloseHandle();
3、关闭文件内核对象。
CloseHandle();
然后有个C+的示例：
- /************************************************************************/
- /* 内存映射一 */
- /*程序演示了如何把一个已存在的文件映射到内存中，并倒转文件内容 */
- /*转载请注明文章来自:http://blog.csdn.net/windows_nt */
- //************************************************************************/
- #include <Windows.h>
- #include <tchar.h>
- #include <string.h> // For _strrev
- #include <iostream>
- #include <CommDlg.h>
- typedef TCHAR *PTSTR;
- #define FILENAME TEXT("FILEREV.DAT")
- BOOL FileReverse(PCTSTR pszPathname, PBOOL pfIsTextUnicode)
- {
- *pfIsTextUnicode = FALSE; // Assume text is Unicode
- // Open the file for reading and writing.
- HANDLE hFile = CreateFile(pszPathname, GENERIC_WRITE | GENERIC_READ, 0,
- NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
- if (hFile == INVALID_HANDLE_VALUE)
- {
- printf("File could not be opened.");
- return(FALSE);
- }
- // Get the size of the file (I assume the whole file can be mapped).
- DWORD dwFileSize = GetFileSize(hFile, NULL);
- // Create the file-mapping object. The file-mapping object is 1 character
- // bigger than the file size so that a zero character can be placed at the
- // end of the file to terminate the string (file). Because I don't yet know
- // if the file contains ANSI or Unicode characters, I assume worst case
- // and add the size of a WCHAR instead of CHAR.
- HANDLE hFileMap = CreateFileMapping(hFile, NULL, PAGE_READWRITE,
- 0, dwFileSize + sizeof(WCHAR), NULL);
- if (hFileMap == NULL)
- {
- printf("File map could not be opened.");
- CloseHandle(hFile);
- return(FALSE);
- }
- // Get the address where the first byte of the file is mapped into memory.
- PVOID pvFile = MapViewOfFile(hFileMap, FILE_MAP_WRITE, 0, 0, 0);
- if (pvFile == NULL)
- {
- printf("Could not map view of file.");
- CloseHandle(hFileMap);
- CloseHandle(hFile);
- return(FALSE);
- }
- // Does the buffer contain ANSI or Unicode?
- int iUnicodeTestFlags = -1; // Try all tests
- *pfIsTextUnicode = IsTextUnicode(pvFile, dwFileSize, &iUnicodeTestFlags);
- if (!*pfIsTextUnicode)
- {
- // For all the file manipulations below, we explicitly use ANSI
- // functions because we are processing an ANSI file.
- // Put a zero character at the very end of the file.
- PSTR pchANSI = (PSTR) pvFile;
- pchANSI[dwFileSize / sizeof(CHAR)] = 0;
- // Reverse the contents of the file.
- _strrev(pchANSI);
- // Convert all "\n\r" combinations back to "\r\n" to
- // preserve the normal end-of-line sequence.
- pchANSI = strchr(pchANSI, '\n'); // Find first '\n'.
- while (pchANSI != NULL)
- {
- // We have found an occurrence....
- *pchANSI++ = '\r'; // Change '\n' to '\r'.
- *pchANSI++ = '\n'; // Change '\r' to '\n'.
- pchANSI = strchr(pchANSI, '\n'); // Find the next occurrence.
- }
- }
- else
- {
- // For all the file manipulations below, we explicitly use Unicode
- // functions because we are processing a Unicode file.
- // Put a zero character at the very end of the file.
- PWSTR pchUnicode = (PWSTR) pvFile;
- pchUnicode[dwFileSize / sizeof(WCHAR)] = 0;
- if ((iUnicodeTestFlags & IS_TEXT_UNICODE_SIGNATURE) != 0) {
- // If the first character is the Unicode BOM (byte-order-mark),
- // 0xFEFF, keep this character at the beginning of the file.
- pchUnicode++;
- }
- // Reverse the contents of the file.
- _wcsrev(pchUnicode);
- // Convert all "\n\r" combinations back to "\r\n" to
- // preserve the normal end-of-line sequence.
- pchUnicode = wcschr(pchUnicode, L'\n'); // Find first '\n'.
- while (pchUnicode != NULL) {
- // We have found an occurrence....
- *pchUnicode++ = L'\r'; // Change '\n' to '\r'.
- *pchUnicode++ = L'\n'; // Change '\r' to '\n'.
- pchUnicode = wcschr(pchUnicode, L'\n'); // Find the next occurrence.
- }
- }
- // Clean up everything before exiting.
- UnmapViewOfFile(pvFile);
- CloseHandle(hFileMap);
- // Remove trailing zero character added earlier.
- SetFilePointer(hFile, dwFileSize, NULL, FILE_BEGIN);
- SetEndOfFile(hFile);
- CloseHandle(hFile);
- return(TRUE);
- }
- void main()
- {
- //当前目录下，必须是数字或字母且为回车结束，不然，转换出来是乱码
- PTCHAR szPathname = _T("123.txt");
- // Make copy of input file so that we don't destroy it
- if (!CopyFile(szPathname, FILENAME, FALSE))
- {
- printf("New file could not be created.");
- return;
- }
-
- BOOL fIsTextUnicode;
- if (FileReverse(FILENAME, &fIsTextUnicode))
- {
- // Spawn Notepad to see the fruits of our labors.
- STARTUPINFO si = { sizeof(si) };
- PROCESS_INFORMATION pi;
- TCHAR sz[] = TEXT("Notepad ") FILENAME;
- if (CreateProcess(NULL, sz,
- NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi))
- {
- CloseHandle(pi.hThread);
- CloseHandle(pi.hProcess);
- }
- }
- DeleteFile(FILENAME);
- return;
- }
不知用VBA如何实现 |
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楼主: aman1516
沪公网安备 31011702000001号 沪ICP备11019229号-2
发表于 2018-11-23 08:46
