Visual Basic 6 Black Book:File Handling And File Controls
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Now that we’ve created a TextStream, we can write to it, as we’ll see later in this chapter.

Opening A TextStream
To open a TextStream, you use the FileSystemObject’s OpenTextFile method:


FileSystemObject.OpenTextFile( filename[, iomode[, create[, format]]])


Here are what the arguments to OpenTextFile mean:

•  filename—The file to open.
•  iomode—Indicates input/output mode. Can be one of two constants, either ForReading or ForAppending.
•  create—Boolean value that indicates whether a new file can be created if the specified file doesn’t exist. The value is True if a new file is created; False if it isn’t created. The default is False.
•  format—One of three values used to indicate the format of the opened file. If omitted, the file is opened as ASCII.

Here’s an example where we open a TextStream object corresponding to a file named file.txt:



Private Sub Command2_Click()
Dim FileSystemObject, TextStream As Object

Set FileSystemObject = CreateObject("Scripting.FileSystemObject")
Set TextStream = FileSystemObject.OpenTextFile("c:\file.txt")
End Sub


After you’ve opened a TextStream object, you can read from it, as we’ll see later in this chapter.

Writing To A TextStream
To write to a TextStream object, you use one of these methods:



Write( string)
WriteLine([ string])


Here’s an example where we create a file named file.txt and write a string, “Here is some text!” to that file. First, we create a new TextStream:



Private Sub Command1_Click()
Dim FileSystemObject, TextStream As Object

Set FileSystemObject = CreateObject("Scripting.FileSystemObject")
Set TextStream = FileSystemObject.CreateTextFile("c:\file.txt", True)
...


Then we write our line of text to the file and close that file:



Private Sub Command1_Click()
Dim FileSystemObject, TextStream As Object

Set FileSystemObject = CreateObject("Scripting.FileSystemObject")
Set TextStream = FileSystemObject.CreateTextFile("c:\file.txt", True)
TextStream.WriteLine ("Here is some text!")
TextStream.Close
End Sub


Reading From A TextStream
To read from a TextStream object, you use one of these methods; note that the Read method lets you specify how many characters to read:


Read( numbercharacters)
ReadAll
ReadLine


Each of these methods returns the text read. Let’s see an example. In this case, we’ll open a file, file.txt, and read one line from it, displaying that line in a text box. First, we create a TextStream object for that file:



Private Sub Command1_Click()
Dim FileSystemObject, TextStream As Object

Set FileSystemObject = CreateObject("Scripting.FileSystemObject")
Set TextStream = FileSystemObject.OpenTextFile("c:\file.txt")
...


Next, we use the ReadLine method to read a line from the file and display it in a text box, Text1, and close the TextStream:


Private Sub Command1_Click()
Dim FileSystemObject, TextStream As Object

Set FileSystemObject = CreateObject("Scripting.FileSystemObject")
Set TextStream = FileSystemObject.OpenTextFile("c:\file.txt")

Text1.Text = TextStream.ReadLine
TextStream.Close
End Sub


Closing A TextStream
When you’re finished working with a TextStream object, you close it using the Close method. In the following example, we write to a file, file.txt, using a TextStream object and then close that TextStream (and therefore the file) using Close (this method takes no arguments):


Private Sub Command1_Click()
Dim FileSystemObject, TextStream As Object
Set FileSystemObject = CreateObject("Scripting.FileSystemObject")
Set TextStream = FileSystemObject.CreateTextFile("c:\file.txt", True)

TextStream.WriteLine ("Here is some text!")
TextStream.Close
End Sub






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