Lesson 7 : Working with Text files

In our routine as an administrator, we routinely work with text files. Let us try to understand how to work with them.

A usual logic would be

- Open the file, Loop line by line, display the contents (or process them)

Example 1:

In this example, we try to display the contents of the file that is passed as a parameter at the command line. I have not done validations and assume that a file name is already there. You can add three validations, first check if there is an argument. Second check if the file exists. Third check if it is a text file.  I have a sample file called “sample.txt” in the same folder as the program.

Const ReadMode=1 dim fso dim fstext dim txtline set fso=CreateObject("Scripting.FileSystemObject") set fstext=fso.OpenTextFile(wscript.arguments(0),ReadMode) do until fstext.AtEndOfStream     txtline=fstext.ReadLine     wscript.echo txtline loop

Let us check the output

C:\scripts\file-io>01-show-contents.vbs sample.txt //nologo The quick fox jumped over the lazy dog. The hare and the turtle were friends in the forest. Early bird gets the worm. C:\scripts\file-io>

Let us make it more useful. At the end, let us say we want to display the total lines in this file.

Const ReadMode=1 dim fso dim fstext dim txtline dim lines lines=0 set fso=CreateObject("Scripting.FileSystemObject") set fstext=fso.OpenTextFile(wscript.arguments(0),ReadMode) do until fstext.AtEndOfStream     txtline=fstext.ReadLine     wscript.echo txtline     lines=lines+1 loop wscript.echo "--------------------------------------end of file" wscript.echo "Lines in the file " & lines

C:\scripts\file-io>01-show-contents.vbs sample.txt //nologo The quick fox jumped over the lazy dog. The hare and the turtle were friends in the forest. Early bird gets the worm. --------------------------------------end of file Lines in the file 4 C:\scripts\file-io>

What if we needed the lines and words.

a. Use the split function, it splits a string and returns an array

b. use the ubound function to check how many elements are there in the array, and add 1

Const ReadMode=1 dim fso dim fstext dim txtline dim lines, words dim strword lines=0 words=0 set fso=CreateObject("Scripting.FileSystemObject") set fstext=fso.OpenTextFile(wscript.arguments(0),ReadMode) do until fstext.AtEndOfStream     txtline=fstext.ReadLine     strword=split(txtline)     words=words+ubound(strword) +1     wscript.echo txtline     lines=lines+1 loop wscript.echo "--------------------------------------end of file" wscript.echo "Lines in the file " & lines wscript.echo "Number of words   " & words

Sample Output of the same file

C:\scripts\file-io>01-show-contents.vbs sample.txt //nologo The quick fox jumped over the lazy dog. The hare and the turtle were friends in the forest. Early bird gets the worm. --------------------------------------end of file Lines in the file 4 Number of words   23 C:\scripts\file-io>

Let us make it more complete. We do the following changes, we pass the parameter filename with a number, 1=show file, 2=show lines, 3=show words, 4=show all

Code

Const ReadMode=1 dim fso dim fstext dim txtline dim lines, words dim strword lines=0 words=0 dim Oput oput=int(wscript.arguments(1)) set fso=CreateObject("Scripting.FileSystemObject") set fstext=fso.OpenTextFile(wscript.arguments(0),ReadMode) do until fstext.AtEndOfStream     txtline=fstext.ReadLine     strword=split(txtline)     words=words+ubound(strword) +1     if oput=1 or oput=4 then         wscript.echo txtline     end if     lines=lines+1 loop if oput=1 or oput=4 then     wscript.echo "--------------------------------------end of file" end if if oput=2 or oput=3 or oput=4 then     wscript.echo "Lines in the file " & lines end if if oput=3 or oput=4 then     wscript.echo "Number of words   " & words end if

Various Runs

C:\scripts\file-io>01-show-contents.vbs sample.txt 1 //nologo The quick fox jumped over the lazy dog. The hare and the turtle were friends in the forest. Early bird gets the worm. --------------------------------------end of file C:\scripts\file-io>01-show-contents.vbs sample.txt 2 //nologo Lines in the file 4 C:\scripts\file-io>01-show-contents.vbs sample.txt 3 //nologo Lines in the file 4 Number of words   23 C:\scripts\file-io>01-show-contents.vbs sample.txt 4 //nologo The quick fox jumped over the lazy dog. The hare and the turtle were friends in the forest. Early bird gets the worm. --------------------------------------end of file Lines in the file 4 Number of words   23 C:\scripts\file-io>

We build more on this in the subsequent chapters.