FtpOpenFileW function (wininet.h)

Initiates access to a remote file on an FTP server for reading or writing.


  [in] HINTERNET hConnect,
  [in] LPCWSTR   lpszFileName,
  [in] DWORD     dwAccess,
  [in] DWORD     dwFlags,
  [in] DWORD_PTR dwContext


[in] hConnect

Handle to an FTP session.

[in] lpszFileName

Pointer to a null-terminated string that contains the name of the file to be accessed.

[in] dwAccess

File access. This parameter can be GENERIC_READ or GENERIC_WRITE, but not both.

[in] dwFlags

Conditions under which the transfers occur. The application should select one transfer type and any of the flags that indicate how the caching of the file will be controlled.

The transfer type can be one of the following values.

Value Meaning
Transfers the file using FTP's ASCII (Type A) transfer method. Control and formatting information is converted to local equivalents.
Transfers the file using FTP's Image (Type I) transfer method. The file is transferred exactly as it exists with no changes. This is the default transfer method.
Transfers the file as ASCII.
Transfers the file as binary.

The following values are used to control the caching of the file. The application can use one or more of these values.

Value Meaning
Forces a reload if there was no Expires time and no LastModified time returned from the server when determining whether to reload the item from the network.
Causes a temporary file to be created if the file cannot be cached.
Forces a download of the requested file, object, or directory listing from the origin server, not from the cache.
Reloads HTTP resources if the resource has been modified since the last time it was downloaded. All FTP resources are reloaded.

Windows XP and Windows Server 2003 R2 and earlier:  Gopher resources are also reloaded.

[in] dwContext

Pointer to a variable that contains the application-defined value that associates this search with any application data. This is only used if the application has already called InternetSetStatusCallback to set up a status callback function.

Return value

Returns a handle if successful, or NULL otherwise. To retrieve a specific error message, call GetLastError.


After calling FtpOpenFile and until calling InternetCloseHandle, all other calls to FTP functions on the same FTP session handle will fail and set the error message to ERROR_FTP_TRANSFER_IN_PROGRESS. After the calling application has finished using the HINTERNET handle returned by FtpOpenFile, it must be closed using the InternetCloseHandle function.

Only one file can be open in a single FTP session. Therefore, no file handle is returned and the application simply uses the FTP session handle when necessary.

The lpszFileName parameter can be either a partially or fully qualified file name relative to the current directory.

Like all other aspects of the WinINet API, this function cannot be safely called from within DllMain or the constructors and destructors of global objects.

Note  WinINet does not support server implementations. In addition, it should not be used from a service. For server implementations or services use Microsoft Windows HTTP Services (WinHTTP).


The wininet.h header defines FtpOpenFile 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.


Minimum supported client Windows 2000 Professional [desktop apps only]
Minimum supported server Windows 2000 Server [desktop apps only]
Target Platform Windows
Header wininet.h
Library Wininet.lib
DLL Wininet.dll

See also

FTP Sessions

WinINet Functions