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File Attribute Constants

This topic describes the file attribute constants that are used by various file I/O functions in the Win32 API.

Note: When specifying file attributes, you can combine multiple flags by using the bitwise OR operator (|).

Overview

File attributes are used to describe the characteristics of files and directories. These attributes can be set or retrieved using functions like CreateFile, GetFileAttributes, and SetFileAttributes. Understanding these constants is crucial for managing files programmatically on Windows.

Common File Attribute Constants

Constant Value (Hex) Description
FILE_ATTRIBUTE_READONLY 0x00000001 The file or directory is read-only. Applications can only access the file or directory to read data. WriteFile and DeleteFile operations fail for this file.
FILE_ATTRIBUTE_HIDDEN 0x00000002 The file or directory is hidden. It is not included in an ordinary directory listing.
FILE_ATTRIBUTE_SYSTEM 0x00000004 The file or directory is a system file. The operating system uses this value to identify essential files.
FILE_ATTRIBUTE_DIRECTORY 0x00000010 This value indicates that the file is a directory.
FILE_ATTRIBUTE_ARCHIVE 0x00000020 The file or directory is an archive file or directory. Applications use this value to distinguish files that should be backed up or archived.
FILE_ATTRIBUTE_ENCRYPTED 0x00000040 This attribute and its index value are reserved for future use.
FILE_ATTRIBUTE_NORMAL 0x00000080 This attribute is for a file or directory that does not have any other attributes set. This attribute is valid only on the root of a drive, and then only if the file is not hidden, system, or archive.
FILE_ATTRIBUTE_TEMPORARY 0x00000100 The file is a temporary file. File systems avoid writing temporary files to disk. This flag helps optimize file I/O by keeping temporary files in memory.
FILE_ATTRIBUTE_SPARSE_FILE 0x00000200 The file is a sparse file. Sparse files are files that contain large blocks of zeros.
FILE_ATTRIBUTE_REPARSE_POINT 0x00000400 The file or directory is a reparse point, which is a block of user-defined data that can be used by a file system filter driver to provide more sophisticated file system functionality.
FILE_ATTRIBUTE_COMPRESSED 0x00000800 The file or directory is compressed. For a file, this means that all of the data in the file is compressed. For a directory, this means that compression is inherited by newly created files and subdirectories.
FILE_ATTRIBUTE_OFFLINE 0x00001000 The data for the file is not immediately available. This attribute indicates that the file data is archived remotely.
FILE_ATTRIBUTE_DATA_ENCRYPTED 0x00008000 The file or directory is encrypted using the Encrypting File System (EFS).
FILE_ATTRIBUTE_INTEGRITY_STREAM 0x00004000 This attribute is reserved for future use.
FILE_ATTRIBUTE_NO_SCRUB_DATA 0x00008000 This attribute is reserved for future use.

Example Usage (Conceptual C++)

Here's a conceptual example of how you might use these constants in C++:

#include <windows.h>

HANDLE hFile = CreateFile(
L"MyFile.txt",
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,
NULL
);

if (hFile == INVALID_HANDLE_VALUE) {
// Handle error
DWORD error = GetLastError();
} else {
// File opened successfully
// ... read from file ...
CloseHandle(hFile);
}

See Also