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OpenFile The OpenFile function creates, opens, reopens, or deletes a file.
VB4-32,5,6
Declare Function OpenFile Lib "kernel32" Alias "OpenFile" (ByVal lpFileName As String, lpReOpenBuff As OFSTRUCT, ByVal wStyle As Long) As Long |
VB.NET
System.IO.File.Open |
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Operating Systems Supported |
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Requires Windows NT 3.1 or later; Requires Windows 95 or later |
- lpFileName
Points to a null-terminated string that names the file to be opened. The string must consist of characters from the Windows 3.x character set. The OpenFile function does not support Unicode filenames.
- lpReOpenBuff
Points to the OFSTRUCT structure that receives information about the file when it is first opened. The structure can be used in subsequent calls to the OpenFile function to refer to the open file.
The OFSTRUCT structure contains a pathname string member whose length is limited to OFS_MAXPATHNAME characters. OFS_MAXPATHNAME is currently defined to be 128. Because of this, you cannot use the OpenFile function to open a file whose path length exceeds 128 characters. The CreateFile function does not have such a path length limitation.
- uStyle
Specifies the action to take. The following values can be combined by using the bitwise OR operator:
OF_CANCEL
Ignored. In the Win32 application programming interface (API), the OF_PROMPT style produces a dialog box containing a Cancel button.
OF_CREATE
Creates a new file. If the file already exists, it is truncated to zero length.
OF_DELETE
Deletes the file.
OF_EXIST
Opens the file and then closes it. Used to test for a file’s existence.
OF_PARSE
Fills the OFSTRUCT structure but carries out no other action.
OF_PROMPT
Displays a dialog box if the requested file does not exist. The dialog box informs the user that Windows cannot find the file, and it contains Retry and Cancel buttons. Choosing the Cancel button directs OpenFile to return a file-not-found error message.
OF_READ
Opens the file for reading only.
OF_READWRITE
Opens the file for reading and writing.
OF_REOPEN
Opens the file using information in the reopen buffer.
OF_SHARE_COMPAT
For MS-DOS-based file systems using the Win32 API, opens the file with compatibility mode, allowing any process on a specified computer to open the file any number of times. Other efforts to open with any other sharing mode fail.
Windows NT: This flag is mapped to the CreateFile function's FILE_SHARE_READ | FILE_SHARE_WRITE flags.
OF_SHARE_DENY_NONE
Opens the file without denying read or write access to other processes. On MS-DOS-based file systems using the Win32 API, if the file has been opened in compatibility mode by any other process, the function fails.
Windows NT: This flag is mapped to the CreateFile function's FILE_SHARE_READ | FILE_SHARE_WRITE flags.
OF_SHARE_DENY_READ
Opens the file and denies read access to other processes. On MS-DOS-based file systems using the Win32 API, if the file has been opened in compatibility mode or for read access by any other process, the function fails. Windows NT: This flag is mapped to the CreateFile function's FILE_SHARE_WRITE flag.
OF_SHARE_DENY_WRITE
Opens the file and denies write access to other processes. On MS-DOS-based file systems using the Win32 API, if the file has been opened in compatibility mode or for write access by any other process, the function fails.
Windows NT: This flag is mapped to the CreateFile function's FILE_SHARE_READ flag.
OF_SHARE_EXCLUSIVE
Opens the file with exclusive mode, denying both read and write access to other processes. If the file has been opened in any other mode for read or write access, even by the current process, the function fails.
OF_VERIFY
Verifies that the date and time of the file are the same as when it was previously opened. This is useful as an extra check for read-only files.
OF_WRITE
Opens the file for writing only. |
If the function succeeds, the return value specifies a file handle.
If the function fails, the return value is HFILE_ERROR. To get extended error information, call GetLastError. |
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