Microsoft WSH and VBScript Programming for the Absolute Beginner Part 27 pot

‘Description: This script demonstrates how to create, open, and write ‘a line of text to a text file.. In other words, if you open a file in ForReadingmode, your script cannot write new

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‘Description: This script demonstrates how to create, open, and write

‘a line of text to a text file.

‘*************************************************************************

‘Initialization Section

Option Explicit

Dim objFso, objFileHandle, strFileName

Set objFso = WScript.CreateObject(“Scripting.FileSystemObject”)

strFileName = “C:\Temp\Sample.txt”

‘Main Processing Section

OpenTextFile()

WriteTextOutput()

CloseTextFile()

TerminateScript()

‘Procedure Section

Function OpenTextFile()

‘If exists open it in append mode, otherwise create and open a new file

If (objFso.FileExists(strFileName)) Then

Set objFileHandle = objFso.OpenTextFile(strFileName, 8)

Else

Set objFileHandle = objFso.OpenTextFile(strFileName, 2, “True”)

End If

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End Function

Function WriteTextOutput()

‘Write 3 lines of text to the text file

objFileHandle.WriteLine “Once upon a time there was a little boy who”

objFileHandle.WriteLine “lived in a shoe Unfortunately it was two sizes”

objFileHandle.WriteLine “too small!”

End Function

Function CloseTextFile()

‘Close the file when done working with it

objFileHandle.Close()

End Function

Function TerminateScript()

‘Stop the execution of this script

WScript.Quit()

End Function

It is very important that you always remember to close any open files before allowing your scripts to end You do this by using the FileSystemObjectobject’s Close()method as shown here:

If you forget to close a file after working with it, the file might become corrupted because the end-of-file marker has not been created for it

You can only open a file using one mode at a time In other words, if you open a file in ForReadingmode, your script cannot write new text to the file unless you first close the file and then open it again in ForWritingmode

T R A P

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If you save and run this script and then open the Sample.txtfile using Windows Notepad, you’ll see the output shown in Figure 8.6

Writing to Files

You have a number of different options when it comes to how your VBScripts write text to files:

• Writing one or more characters at a time

• Writing a line at a time

• Writing blank lines

Writing text one or more characters at a time is good when you need to carefully format text output, such as when you want to create reports with data lined up in columns On the other hand, writing out one line of text at a time is convenient when the format is more free form Finally, inserting or writing blank lines into text files helps you improve the file’s appearance, such as adding space between the heading and the text in a formal report

Writing Characters

To write text to a file one or more characters at a time, you need to use the FileSystemObject object’s Write()method This method does not append a carriage return to the end of any text that it writes If two back-to-back write operations are performed using the Write() method, for example, the text from the second write operation is inserted into the text file

Figure 8.6

Writing to a

new or existing

text file.

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on the same line immediately following the text written by the first write operation To see how this works, take at look at the following example:

Set objFileHandle = _

objFso.OpenTextFile(“C:\Temp\Sample.txt”, 2, “True”)

objFileHandle.Write(“Once upon a time there “)

objFileHandle.Write(“were three little bears.”)

If you save and run this example, you’ll see that the output added to the text file by the script is placed on the same line as shown in Figure 8.7

Writing Lines

You can modify the previous example to write text output to the file a line at a time by replacing the Write()method with the WriteLine()method:

objFileHandle.WriteLine(“Once upon a time there were three little bears.”)

If you save and run this example, you’ll find that the results are almost exactly the same as those produced by the previous example The one difference is that the cursor is now posi-tioned at the beginning of the next row in the text file when you run this example, whereas the cursor was left at the end of the first row when you ran the previous example This is because the WriteLine()method automatically appends a linefeed to the end of each write operation

Figure 8.7

Writing

characters

to a text file.

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Adding Blank Lines

You can add blank lines to the output generated by your VBScripts to make it look better by using the FileSystemObject object’s WriteBlankLines() method This method executes by writing a blank line and then advancing the cursor down to the beginning of the next row

in the file

The following example demonstrates how to use the FileSystemObject object’s Write-BlankLines()method:

Set strInputFile = objFso.GetFile(“C:\VBScriptGames\Hangman.vbs”)

objFileHandle.WriteBlankLines(1)

objFileHandle.WriteLine(“C:\VBScriptGames\Hangman.vbs Properties”)

objFileHandle.WriteLine(“———————————————————————-”)

objFileHandle.WriteLine(“Creation Date: “ & strInputFile.DateCreated)

objFileHandle.WriteLine(“Last Modified: “ & strInputFile.DateLastModified)

objFileHandle.WriteLine(“———————————————————————-”)

Figure 8.8 shows how the Sample.txtfile looks after the script has been executed

Figure 8.8

Blank lines

improve the

presentation of

reports created

by your

VBScripts.

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Reading from Files

VBScript makes it just about as easy to read from a file as it is to write to one However, before you attempt to read or process the contents of a text file, you should first make sure the file has data in it If the file has no data, opening the file and attempting to read it is pointless

You can use the TestStreamobject’s AtEndOfStreamproperty to determine whether a file con-tains data Not only should you check the AtEndOfStreamproperty before you begin reading

a file, but your script should continue to check this property before each additional read operation to make sure data is still in the file for the script to read In other words, you need

to keep checking to make sure that your script has not reached the end-of-file marker

To demonstrate how all this works, let’s build an example For starters, create a new VBScript and add the following statements to it:

Dim objFso, objFileHandle, strDisplayString

Set objFileHandle = objFso.OpenTextFile(“C:\Temp\Sample.txt”, 1)

The first statement defines variables to be used by the script The next statement instanti-ates the FileSystemObject The third statement sets up an object reference to the Sample.txt file and opens it in ForReadingmode Now add the following statements to the script:

Do While objFileHandle.AtEndOfStream = False

strDisplayString = strDisplayString & objFileHandle.ReadLine() & vbCrLf

Loop

MsgBox strDisplayString

The first statement sets up a Do While loop that checks on each iteration to determine whether or not the end-of-file marker has been reached As long as the end of the file has not been reached, another line of the file is read and appended to the end of a variable named strDisplayString

Finally, close the file by adding the following statement:

objFileHandle.Close

If you run this script, you’ll see output similar to that shown in Figure 8.9

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This example showed you how to read an entire file, a line at a time Other options that are available to you when reading files include

• Skipping lines

• Reading one or more characters at a time

• Reading the entire file at one time

Skipping Lines

Often text reports and other files begin with some type of heading or other information that you might not be particularly interested in In these cases, you can skip the reading of these lines using the FileSystemObjectobject’s Skip()and SkipLine() methods The Skip() method allows your script to skip a specific number of characters at a time, whereas the SkipLine()allows your script to skip entire lines

To use the Skip()method, you must pass it the number of characters that you want skipped

as demonstrated here:

objFileHandle.Skip(25)

The SkipLine() method does not accept any arguments, so it can only be used to skip one line at a time However, by wrapping the execution of this method up within a loop, you can skip as many lines as you want as demonstrated here:

For intCounter = 1 To 5

objFileHandle.SkipLine()

Creating a

VBScript that

reads and

displays the

content of

text files.

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Reading Files Character by Character

To read a file one or more characters at a time, you need to work with the FileSystemObject object’s Read()method This might be necessary for reading files with fixed length data For example, you might have a report file that lists a certain category or information in a col-umn that begins at character position 20 and ends at character position 30 on each line of the report Using the Read()method, you could develop a VBScript that reads the file and pulls out only the information stored in that column for each line of the file

To get a glimpse of the Read()method in action, consider the following example This script uses

a Forloop and the SkipLine()method to skip the reading of the first 5 lines of the Sample.txt file The Skip() method skips the first 15 characters on the next line in the file (line 6) The Read()method reads the next 22 characters from the file The file is then closed and the text that was read from the file is displayed

Dim objFso, objFileHandle, intCounter, strDisplayString

For intCounter = 1 To 5

objFileHandle.SkipLine()

strDisplayString = objFileHandle.Read(22)

objFileHandle.Close

MsgBox “C:\Temp\Sample.txt was created on “ & strDisplayString

Reading a File All at Once

Sometimes all you need to do is read an entire file in a single operation, such as when the file to be read is already formatted to produce the output that you want You can do this using the FileSystemObjectobject’s ReadAll()method as demonstrated here:

Dim objFso, objFileHandle, strDisplayString

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strDisplayString = objFileHandle.ReadAll()

MsgBox strDisplayString

As you can see, the script reads the entire file using just one ReadAll()operation and then displays what it reads using a MsgBox()statement The output displayed when you run this script is exactly the same as that shown previously in Figure 8.9, in which the script read the entire text file a line at a time before displaying the file’s contents

Managing Files and Folders

In addition to using VBScript and the WSH to read and write to and from text files, you can also use them to help administer all your files and folder By administer, I mean to help keep them organized Or more specifically, to automate the organization process For example, if your computer is connected to a local area network, you can create a VBScript that makes copies of all the files it finds in certain folders and stores them on a network server This way, if something ever happens to your original files, you can always recover by retrieving a backup copy

The FileSystemObjectprovides several methods for developing scripts that can automate file administration:

• CopyFile() Copies one or more files

• MoveFile() Moves one or more files

• DeleteFile().Deletes one or more files

• FileExists() Determines whether or not a file exists

The FileSystemObject also provides a large collection of methods for automating folder administration:

• CopyFolder() Copies one or more folders

• MoveFolder() Moves one or more folders

• DeleteFolder() Deletes one or more folders

• FolderExists() Determines whether or not a folder exists

• CreateFolder() Creates a new folder

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As an alternative to working with methods belonging to the FileSystemObject, you also can work with methods that jointly belong to the Fileand Folder objects:

• Copy() Copies a single file or folder

• Delete() Removes a single file or folder

• Move() Moves a single file or folder

There are a few drawbacks to these methods First, using these methods requires that you instantiate both the FileSystemObjectand the Fileor Folder object, which is just a little more work Second, they work with just one file at a time as opposed to the methods belonging to the FileSystemObject, which can work on more than one file or folder at a time Finally, because the Fileand Folderobjects share the same methods, it’s sometimes easy to make a mistake and accidentally mess things up For example, if you have a file and a folder in the same location with the same or a similar name, it’s easy to accidentally delete the wrong one

Copying, Moving, and Deleting Files

Using the FileSystemObject object’s CopyFile() method, you can create VBScript that can copy one or more files as demonstrated in the following example:

Dim objFso

objFso.CopyFile “C:\Temp\Sample.txt”, “C:\VBScriptGames\Sample.txt”

In this example, a file named Sample.txtlocated in the Tempfolder on the computer C:drive

is copied to the VBScriptGamesfolder located on the C:drive By modifying this example, as shown here, you can change the script so that it copies more than one file Specifically, this example results in all files named Samplebeing copied, regardless of their file extensions Dim objFso

objFso.CopyFile “C:\Temp\Sample.*”, “C:\VBScriptGames”

Wildcard characters make it possible to copy, move, or delete more than one file or folder at a time The ?and *wildcard characters enable pattern matching The ?character is used to specify a single character match The * character is used to match up against an unlimited number of characters For example, specifying *.txtresults in a match with all files that have a .txtfile extension Specifying sampl?.txtresults in a match only with files that have a six-character-long file name, Samplas the first five characters, and a .txtfile extension

T R I C K

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