创建临时文件的方法有很多种：每种方法背后的情况是什么？
我的 C++ winAPI 应用程序需要在将文件上传到服务器之前创建一个临时文件。所以我搜索了创建临时文件和临时文件的方法。发现有很多方法可以做到这一点。
你能告诉我：对于下面的每一种方法，我应该在什么场景下使用该方法？哪种方法最适合我的需求？
方法 1：
// Using CreateFile()
CreateFile( "myfile.txt", GENERIC_ALL, ..., FILE_ATTRIBUTE_TEMPORARY, 0); // removed unecessary parameters
方法 2：
// I think that GetTempFileName also creates the file doesn't it? Not just generates a unique fileName?
// Gets the temp path env string (no guarantee it's a valid path).
dwRetVal = GetTempPath(MAX_PATH, // length of the buffer
lpTempPathBuffer); // buffer for path
// Generates a temporary file name.
uRetVal = GetTempFileName(lpTempPathBuffer, // directory for tmp files
TEXT("DEMO"), // temp file name prefix
0, // create unique name
szTempFileName); // buffer for name
方法 3：
// Create a file & use the flag DELETE_ON_CLOSE. So its a temporary file that will delete when the last HANDLE to it closes
HANDLE h_file = CreateFile( tmpfilename, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, NULL );
为什么有不止一种方法来创建临时文件。举例来说，在什么情况下我会想使用方法 2 而不是方法 1？
My C++ winAPI application has a need to create a temporary file prior to uploading the file to a server. So I have searched ways to create a temporary file & found there are many ways to do this.
Can you tell me: For each of the following methods below, in which scenario am I supposed to use that method? And which method would best suite my needs?
Method 1:
// Using CreateFile()
CreateFile( "myfile.txt", GENERIC_ALL, ..., FILE_ATTRIBUTE_TEMPORARY, 0); // removed unecessary parameters
Method 2:
// I think that GetTempFileName also creates the file doesn't it? Not just generates a unique fileName?
// Gets the temp path env string (no guarantee it's a valid path).
dwRetVal = GetTempPath(MAX_PATH, // length of the buffer
lpTempPathBuffer); // buffer for path
// Generates a temporary file name.
uRetVal = GetTempFileName(lpTempPathBuffer, // directory for tmp files
TEXT("DEMO"), // temp file name prefix
0, // create unique name
szTempFileName); // buffer for name
Method 3:
// Create a file & use the flag DELETE_ON_CLOSE. So its a temporary file that will delete when the last HANDLE to it closes
HANDLE h_file = CreateFile( tmpfilename, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_DELETE_ON_CLOSE, NULL );
Why are there more than 1 way to create a temp file. And, for example, what is the situation where I would want to use, say, method 2 over method 1?
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FILE_ATTRIBUTE_TEMPORARY只是告诉Windows，如果有足够的缓存，就不要将文件内容写入磁盘，因为该文件是临时的，没有其他进程会使用它。FILE_FLAG_DELETE_ON_CLOSE顾名思义，当您关闭文件时，它会被自动删除。这保证了这将是暂时的。GetTempFilename为临时文件创建一个名称，并保证该文件名以前未被使用过。创建临时文件时应该使用所有 3 种方法。他们都不干扰其他人。
FILE_ATTRIBUTE_TEMPORARYsimply tells Windows not to bother writing the file contents to disk if there's enough cache, because the file is temporary and no other process will be using it.FILE_FLAG_DELETE_ON_CLOSEmeans just what it says - when you close the file it will be deleted automatically. This guarantees that it will be temporary.GetTempFilenamecreates a name for a temporary file, and guarantees that the filename hasn't been used previously.You should use all 3 methods when creating a temporary file. None of them interferes with the others.
对于方法 #2，如果您使用 0 作为“唯一 ID”，您实际上需要使用 FILE_ATTRIBUTE_TEMPORARY 调用 SetFileAttributes 以使生成的文件成为临时文件，其意义与方法 #1 相同（否则它将是一个普通的 ARCHIVE/NOT_CONTENT_INDEXED 文件。
） GetFileAttributes 或 GetFileInformationByHandle 查看文件实际拥有的属性。
For method #2 if you use 0 for the "unique ID" you actually need to call SetFileAttributes with FILE_ATTRIBUTE_TEMPORARY to make the generated file temporary in the same sense as method #1 (otherwise it will be a normal ARCHIVE/NOT_CONTENT_INDEXED file.)
Use GetFileAttributes or GetFileInformationByHandle to see what attributes the file actually possesses.