introduction
The first step in working with files in Visual Basic is to open the file. This is achieved using the Visual Basic FileStream class. The FileStream constructor accepts the file name to be opened as the first parameter, followed by a number of other parameters defining the mode in which the file is to be opened. These fall into the categories of FileMode, FileAccess and FileShare. The options available as listed in the following tables:
FileMode Options
Mode |
Description |
Append |
If the file exists it is opened. Any writes are appended to the end of the file. |
Create |
Creates a new file, removing old file if it already exists |
CreateNew |
Creates a new file and returns error if file already exists |
Open |
Opens an existing file. Returns error if file does not exist |
OpenOrCreate |
If file already exists it is opened, otherwise a new file is created |
Truncate |
Opens an existing file and deletes all existing content |
FileAccess Options
Mode |
Description |
Read |
Opens the file for reading only. |
ReadWrite |
Opens the file for both reading and writing |
Write |
Opens the file to writing only |
FileShare Options
Mode |
Description |
None |
The file cannot be opened by any other program until it is closed by the current program |
Read |
Other programs may simultaneously open and read from the file, but not write to it. |
ReadWrite |
Other programs may simultaneously open and read and write from/to the file. |
Write |
Other programs may simultaneously open and write to the file, but not read from it. |