SetFileAttributesA function (fileapi.h)

Sets the attributes for a file or directory.

To perform this operation as a transacted operation, use the SetFileAttributesTransacted function.


BOOL SetFileAttributesA(
  [in] LPCSTR lpFileName,
  [in] DWORD  dwFileAttributes


[in] lpFileName

The name of the file whose attributes are to be set.

By default, the name is limited to MAX_PATH characters. To extend this limit to 32,767 wide characters, prepend "\\?\" to the path. For more information, see Naming Files, Paths, and Namespaces.


Starting with Windows 10, Version 1607, you can opt-in to remove the MAX_PATH limitation without prepending "\\?\". See the "Maximum Path Length Limitation" section of Naming Files, Paths, and Namespaces for details.

[in] dwFileAttributes

The file attributes to set for the file.

This parameter can be one or more values, combined using the bitwise-OR operator. However, all other values override FILE_ATTRIBUTE_NORMAL.

Not all attributes are supported by this function. For more information, see the Remarks section.

The following is a list of supported attribute values.

Value Meaning
32 (0x20)
A file or directory that is an archive file or directory. Applications typically use this attribute to mark files for backup or removal.
2 (0x2)
The file or directory is hidden. It is not included in an ordinary directory listing.
128 (0x80)
A file that does not have other attributes set. This attribute is valid only when used alone.
8192 (0x2000)
The file or directory is not to be indexed by the content indexing service.
4096 (0x1000)
The data of a file is not available immediately. This attribute indicates that the file data is physically moved to offline storage. This attribute is used by Remote Storage, which is the hierarchical storage management software. Applications should not arbitrarily change this attribute.
1 (0x1)
A file that is read-only. Applications can read the file, but cannot write to it or delete it. This attribute is not honored on directories. For more information, see "You cannot view or change the Read-only or the System attributes of folders in Windows Server 2003, in Windows XP, or in Windows Vista.
4 (0x4)
A file or directory that the operating system uses a part of, or uses exclusively.
256 (0x100)
A file that is being used for temporary storage. File systems avoid writing data back to mass storage if sufficient cache memory is available, because typically, an application deletes a temporary file after the handle is closed. In that scenario, the system can entirely avoid writing the data. Otherwise, the data is written after the handle is closed.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.


The following table describes how to set the attributes that cannot be set using SetFileAttributes. For a complete list of all file attribute values and their descriptions, see File Attribute Constants.

Attribute How to Set


To set a file's compression state, use the DeviceIoControl function with the FSCTL_SET_COMPRESSION operation.


Reserved; do not use.


Files cannot be converted into directories. To create a directory, use the CreateDirectory or CreateDirectoryEx function.


To create an encrypted file, use the CreateFile function with the FILE_ATTRIBUTE_ENCRYPTED attribute. To convert an existing file into an encrypted file, use the EncryptFile function.


To associate a reparse point with a file or directory, use the DeviceIoControl function with the FSCTL_SET_REPARSE_POINT operation.


To set a file's sparse attribute, use the DeviceIoControl function with the FSCTL_SET_SPARSE operation.

Transacted Operations

If a file is open for modification in a transaction, no other thread can open the file for modification until the transaction is committed. So if a transacted thread opens the file first, any subsequent threads that try modifying the file before the transaction is committed receives a sharing violation. If a non-transacted thread modifies the file before the transacted thread does, and the file is still open when the transaction attempts to open it, the transaction receives the error ERROR_TRANSACTIONAL_CONFLICT.

In Windows 8 and Windows Server 2012, this function is supported by the following technologies.

Technology Supported
Server Message Block (SMB) 3.0 protocol Yes
SMB 3.0 Transparent Failover (TFO) Yes
SMB 3.0 with Scale-out File Shares (SO) Yes
Cluster Shared Volume File System (CsvFS) Yes
Resilient File System (ReFS) Yes


For an example, see Retrieving and Changing File Attributes.


The fileapi.h header defines SetFileAttributes as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.


Requirement Value
Minimum supported client Windows XP [desktop apps | UWP apps]
Minimum supported server Windows Server 2003 [desktop apps | UWP apps]
Target Platform Windows
Header fileapi.h (include Windows.h)
Library Kernel32.lib
DLL Kernel32.dll

See also

File Attribute Constants

File Management Functions



Symbolic Links

Transactional NTFS