在Windows API中只开放了两个允许区分大小写的API：
CreateFile，使用FILE_FLAG_POSIX_SEMANTICS开关；
FindFirstFileEx，使用FIND_FIRST_EX_CASE_SENSITIVE开关。
不过我们可以通过SetFileInformationByHandle来实现文件/文件夹的改名和删除。

此外，在Native API中InitializeObjectAttributes时不指定OBJ_CASE_INSENSITIVE开关，也可以实现区分大小写的功能。

所有的这些开关只有注册表键值obcaseinsensitive设为DWORD:0并且【重新启动】之后才有效。obcaseinsensitive的具体位置是HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Control\\Session Manager\\kernel。

这个键值只影响Windows API（kernel32.dll）和Native API（ntdll.dll）的行为，Windows Subsystem for Linux是通过未公开的内核调用来实现的，不受这个注册表键值影响。

// ConsoleApplication1.cpp: 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <windows.h>
#include <stdio.h>

int main()
{
	HKEY hsubkey;
	DWORD valtype, obcaseinsensitive, dwret;
	LSTATUS lstatus;
	ULONGLONG renbuf1[64], renbuf2[64];
	FILE_RENAME_INFO *ren1, *ren2;
	FILE_DISPOSITION_INFO del1, del2;
	HANDLE hdir1, hdir2;
	HANDLE hfind;
	WIN32_FIND_DATA fd;
	char ansipath[MAX_PATH];

	// 检测系统是否打开了Win32的大小写敏感接口
	hsubkey = NULL;
	RegOpenKey(HKEY_LOCAL_MACHINE, TEXT("SYSTEM\\CurrentControlSet\\Control\\Session Manager\\kernel"), &hsubkey);
	valtype = obcaseinsensitive = 0;
	dwret = sizeof obcaseinsensitive;
	lstatus = RegQueryValueEx(hsubkey, TEXT("obcaseinsensitive"), NULL, &valtype, (LPBYTE)&obcaseinsensitive, &dwret);
	RegCloseKey(hsubkey);
	if (lstatus != ERROR_SUCCESS || valtype != REG_DWORD || dwret != sizeof obcaseinsensitive ||
		obcaseinsensitive != 0)
	{
		printf("HKEY_LOCAL_MACHINE\\CurrentControlSet\\Control\\Session Manager\\kernel\\obcaseinsensitive"
			" must be set to REG_DWORD:0, and you must restart your computer before trying again.\n");
		return 1;
	}

	// 创建两个文件夹
	CreateDirectory(TEXT("G:\\CaseDir_1"), NULL);
	CreateDirectory(TEXT("G:\\casedir_123"), NULL);

	// 改成只有大小写不同的形式
	// 第一个
	hdir1 = CreateFile(TEXT("G:\\CaseDir_1"), GENERIC_READ | GENERIC_WRITE | DELETE,
		FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING,
		FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_POSIX_SEMANTICS, NULL);
	memset(renbuf1, 0, sizeof renbuf1);
	ren1 = (FILE_RENAME_INFO*)renbuf1;
	ren1->ReplaceIfExists = FALSE;
	ren1->RootDirectory = NULL;
	wcscpy(ren1->FileName, L"G:\\CaseDir");
	ren1->FileNameLength = wcslen(ren1->FileName) * sizeof(wchar_t);
	SetFileInformationByHandle(hdir1, FileRenameInfo, &renbuf1, sizeof renbuf1);
	CloseHandle(hdir1);
	// 第二个
	hdir2 = CreateFile(TEXT("G:\\casedir_123"), GENERIC_READ | GENERIC_WRITE | DELETE,
		FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING,
		FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_POSIX_SEMANTICS, NULL);
	memset(renbuf2, 0, sizeof renbuf2);
	ren2 = (FILE_RENAME_INFO*)renbuf2;
	ren2->ReplaceIfExists = FALSE;
	ren2->RootDirectory = NULL;
	wcscpy(ren2->FileName, L"G:\\casedir");
	ren2->FileNameLength = wcslen(ren2->FileName) * sizeof(wchar_t);
	SetFileInformationByHandle(hdir2, FileRenameInfo, &renbuf2, sizeof renbuf2);
	CloseHandle(hdir2);

	// 按照区分大小写的方式查找文件/文件夹
	hfind = FindFirstFileEx(TEXT("G:\\Case*"), FindExInfoStandard, &fd,
		FindExSearchNameMatch, NULL, FIND_FIRST_EX_CASE_SENSITIVE);
	if (hfind != INVALID_HANDLE_VALUE)
	{
		do
		{
#ifdef UNICODE
			WideCharToMultiByte(CP_ACP, 0, fd.cFileName, -1, ansipath, MAX_PATH, NULL, NULL);
#else
			strcpy(ansipath, fd.cFileName);
#endif
			printf("%s\n", ansipath);
		} while (FindNextFile(hfind, &fd));
		FindClose(hfind);
	}

#if 0
	// 改回来
	// 第一个
	hdir1 = CreateFile(TEXT("G:\\CaseDir"), GENERIC_READ | GENERIC_WRITE | DELETE,
		FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING,
		FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_POSIX_SEMANTICS, NULL);
	memset(renbuf1, 0, sizeof renbuf1);
	ren1 = (FILE_RENAME_INFO*)renbuf1;
	ren1->ReplaceIfExists = FALSE;
	ren1->RootDirectory = NULL;
	wcscpy(ren1->FileName, L"G:\\CaseDir_1");
	ren1->FileNameLength = wcslen(ren1->FileName) * sizeof(wchar_t);
	SetFileInformationByHandle(hdir1, FileRenameInfo, &renbuf1, sizeof renbuf1);
	CloseHandle(hdir1);
	// 第二个
	hdir2 = CreateFile(TEXT("G:\\casedir"), GENERIC_READ | GENERIC_WRITE | DELETE,
		FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING,
		FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_POSIX_SEMANTICS, NULL);
	memset(renbuf2, 0, sizeof renbuf2);
	ren2 = (FILE_RENAME_INFO*)renbuf2;
	ren2->ReplaceIfExists = FALSE;
	ren2->RootDirectory = NULL;
	wcscpy(ren2->FileName, L"G:\\casedir_123");
	ren2->FileNameLength = wcslen(ren2->FileName) * sizeof(wchar_t);
	SetFileInformationByHandle(hdir2, FileRenameInfo, &renbuf2, sizeof renbuf2);
	CloseHandle(hdir2);
#else
	// 删掉
	// 第一个
	hdir1 = CreateFile(TEXT("G:\\CaseDir"), GENERIC_READ | GENERIC_WRITE | DELETE,
		FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING,
		FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_POSIX_SEMANTICS, NULL);
	del1.DeleteFile = TRUE;
	SetFileInformationByHandle(hdir1, FileDispositionInfo, &del1, sizeof del1);
	CloseHandle(hdir1);
	// 第二个
	hdir2 = CreateFile(TEXT("G:\\casedir"), GENERIC_READ | GENERIC_WRITE | DELETE,
		FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, NULL, OPEN_EXISTING,
		FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_POSIX_SEMANTICS, NULL);
	del2.DeleteFile = TRUE;
	SetFileInformationByHandle(hdir2, FileDispositionInfo, &del2, sizeof del2);
	CloseHandle(hdir2);
#endif

	return 0;
}</stdio.h></windows.h>