In the previous FAQ, we discussed how the
TextStream objects could be used to read the contents of a text file. In this FAQ, we will
discuss how to write to a text file using these two objects.
Recall that we Opened a text file using the
OpenTextFile method of the
object. In the previous FAQ we talked about two parameters into this function. When dealing with writing
text files, we need to discuss the third. This third parameter is optional, like the second, and is a
boolean value. The new definition of the
OpenTextFile method is:
Note: there is one more optional parameter, but we are only interested in these first three for the time being.
iomode parameter decides what IO mode the file is opened with. The following
values can be used:
These constants are not defined in a text file like the ADO constants are defined in
ADOVBS.inc. Therefore, you should define
the constant you wish to use. For example, if I use the
ForReading constant, you
will see ASP code like:
Create method determines whether or not a new file should be created if the specified
file name (
FullFilePath) does not exist.
Create defaults to
If you try to write to a file that doesn't exist, and
Create is set to
implicitly or explicitly), an error will occur.
TextStream object has the following important methods for writing to text files:
Write(string)- Writes a string to the open text file.
WriteLine([string])- Writes a string to the text file and finishes it off with the new line character.
WriteBlankLines(lines)- Writes a specified number of new line characters.
TextStream object has a
Close method, which should be used when
you have finished writing to the file.
Now, let's look at how we could append a couple of lines to an existing text file,
Note that the
Create parameter will be set to
False here (since it is the
default). If the file
C:\Welcome.txt does not exist, an error will occur. If the file
does exist, however, "Hello, World!" and "This is fun!" will be appended.
Now, what if we want to create a text file with the contents: "Hello, World!" The following code will do that just fine:
Create is set to True, if
C:\SomeFile.txt does not exist, the file will still
be created and "Hello, World!" will be written to the file. Neat, eh?
A closing note: when dealing with IIS, the permissions granted to
are important. For example, if you do not have write permission to the C drive for
IUSR_machinename, an error will occur in the above scripts.
Now that we've discussed how to read and write text files, two common file system operations, in our next FAQ we will discuss another common file system operation: copying, moving, and deleting files.