Opens a file for input or output. The My feature gives you better productivity and performance in file I/O operations than FileOpen. For more information, see My.Computer.FileSystem Object.
Assembly: Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)
public static void FileOpen( int FileNumber, string FileName, OpenMode Mode, OpenAccess Access, OpenShare Share, int RecordLength )
- Type: System.Int32
Required. Any valid file number. Use the FreeFile function to obtain the next available file number.
- Type: System.String
Required. String expression that specifies a file name—may include directory or folder, and drive.
- Type: Microsoft.VisualBasic.OpenMode
Required. Enumeration specifying the file mode: Append, Binary, Input, Output, or Random. (For more information, see OpenMode Enumeration.)
- Type: Microsoft.VisualBasic.OpenAccess
Optional. Enumeration specifying the operations permitted on the open file: Read, Write, or ReadWrite. Defaults to ReadWrite. (For more information, see OpenAccess Enumeration.)
- Type: Microsoft.VisualBasic.OpenShare
Optional. Enumeration specifying the operations not permitted on the open file by other processes: Shared, Lock Read, Lock Write, and Lock Read Write. Defaults to Lock Read Write. (For more information, see OpenShare Enumeration.)
- Type: System.Int32
Optional. Number less than or equal to 32,767 (bytes). For files opened for random access, this value is the record length. For sequential files, this value is the number of characters buffered.
For more detailed information, see the Visual Basic topic FileOpen Function.
The FileOpen function is provided for backward compatibility and may affect performance. For non-legacy applications, the My.Computer.FileSystem object provides better performance. For more information, see File Access with Visual Basic.
You must open a file before any I/O operation can be performed on it. FileOpen allocates a buffer for I/O to the file and determines the mode of access to use with the buffer.
When writing to a file, an application may have to create a file, if the file to which it is trying to write does not exist. To do so, it needs permission for the directory in which the file is to be created. However, if the file specified by FileName does exist, the application needs Write permission only to the file itself. Wherever possible, to help improve security, create the file during deployment and grant Write permission to that file only, instead of to the whole directory. To help improve security, write data to user directories instead of to the root directory or the Program Files directory.
The channel to open can be found by using the FreeFile() function.
This example illustrates various uses of the FileOpen function to enable input and output to a file.
The following code opens the file TestFile in Input mode.
This example opens the file in Binary mode for writing operations only.
The following example opens the file in Random mode. The file contains records of the structure Person.
This code example opens the file in Output mode; any process can read or write to file.
This code example opens the file in Binary mode for reading; other processes cannot read file.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.