GetOpenFileName
The GetOpenFileName function creates an Open dialog box that lets the user specify the drive, directory, and the name of a file or set of files to open.  
 
BOOL GetOpenFileName(
  LPOPENFILENAME lpofn   // initialization data
);
Parameters
lpofn  
[in/out] Pointer to an OPENFILENAME structure that contains information used to initialize the dialog box. When GetOpenFileName returns, this structure contains information about the user's file selection.  
Return Values
If the user specifies a file name and clicks the OK button, the return value is nonzero. The buffer pointed to by the lpstrFile member of the OPENFILENAME structure contains the full path and file name specified by the user.
 
If the user cancels or closes the Open dialog box or an error occurs, the return value is zero. To get extended error information, call the CommDlgExtendedError function, which can return one of the following values:  
 
CDERR_DIALOGFAILURE
CDERR_FINDRESFAILURE
CDERR_NOHINSTANCE
CDERR_INITIALIZATION
CDERR_NOHOOK
CDERR_LOCKRESFAILURE
CDERR_NOTEMPLATE
CDERR_LOADRESFAILURE
CDERR_STRUCTSIZE
CDERR_LOADSTRFAILURE
FNERR_BUFFERTOOSMALL
CDERR_MEMALLOCFAILURE
FNERR_INVALIDFILENAME
CDERR_MEMLOCKFAILURE
FNERR_SUBCLASSFAILURE
 
Remarks
The Explorer-style Open dialog box provides user-interface features that are similar to the Windows Explorer. You can provide an OFNHookProc hook procedure for an Explorer-style Open dialog box. To enable the hook procedure, set the OFN_EXPLORER and OFN_ENABLEHOOK flags in the Flags member of the OPENFILENAME structure and specify the address of the hook procedure in the lpfnHook member.  
 
Windows continues to support the old-style Open dialog box for applications that want to maintain a user-interface consistent with the old-style user-interface. To display the old-style Open dialog box, enable an OFNHookProcOldStyle hook procedure and ensure that the OFN_EXPLORER flag is not set.
 
To display a dialog box that allows the user to select a directory instead of a file, call the SHBrowseForFolder function.
 
Note, when selecting multiple files, the total character limit for the file names depends on the operating system and the version of the function:  
 
Windows 95/98/Me: (only ANSI is supported) no restriction  
Windows NT4 and earlier: 32k limit  
Windows 2000/XP: (ANSI) 32k limit, (Unicode) no restriction  
Windows NT 4.0: The OPENFILENAME structure includes additional members on more recent versions of Windows. However, this causes problems for applications on previous versions of Windows. To use the current header files for applications that must run on Windows NT 4.0, either use the #define "/D_WIN32_WINNT=0x0400" or use OPENFILENAME_SIZE_VERSION_400 for the lStructSize member of OPENFILENAME.
 
Windows 95/98/Me: GetOpenFileNameW is supported by the Microsoft Layer for Unicode. To use this, you must add certain files to your application, as outlined in Microsoft Layer for Unicode on Windows 95/98/Me Systems.
 
Example Code
For an example, see Opening a File.  
 
Requirements  
  Windows NT/2000/XP: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.
  Header: Declared in Commdlg.h; include Windows.h.
  Library: Use Comdlg32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT/2000/XP. Also supported by Microsoft Layer for Unicode.
 
See Also
Common Dialog Box Library Overview, Common Dialog Box Functions, CommDlgExtendedError, GetSaveFileName, OFNHookProc, OFNHookProcOldStyle, OPENFILENAME, SHBrowseForFolder