Difference between revisions of "Working with Files in Visual Basic"
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<td>Write<td>Opens the file to writing only</td> | <td>Write<td>Opens the file to writing only</td> | ||
| + | </table> | ||
| + | |||
| + | === FileShare Options === | ||
| + | |||
| + | <table border="1" cellspacing="0"> | ||
| + | <th>Mode<th>Description</th> | ||
| + | <tr> | ||
| + | <td>None<td>The file cannot be opened by any other program until it is closed by the current program</td> | ||
| + | <tr> | ||
| + | <td>Read<td>Other programs may simultaneously open and read from the file, but not write to it.</td> | ||
| + | <tr> | ||
| + | <td>ReadWrite<td>Other programs may simultaneously open and read and write from/to the file.</td> | ||
| + | <tr> | ||
| + | <td>Write<td>Other programs may simultaneously open and write to the file, but not read from it.</td> | ||
| + | <tr> | ||
</table> | </table> | ||
Revision as of 15:37, 10 August 2007
In the two previous chapters we looked at accessing databases using Visual Basic. Often, a database provides more complexity and functionality than is needed and sometimes a plain text file is more than enough for storing information. In this chapter, therefore, we will look at how to work with files and directories in Visual Basic.
Opening a Text File in Visual Basic
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. Requires FileAccess.Write mode |
| 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 |
| 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. |
