Fixed Formatted Text Files

The invention of a fixed formatted text (flat) file layout started with IBM in the 1960’s. Data sets on the mainframe could be stored in both fixed and variable length records.

A flat file is defined as having one record of data per row that is ended with a new line. Each field inside the record is represented by a fixed number of characters.

While flat files can have either ASCII or EBCDIC encoding, I will be exploring the former. Another generalization of this format is to store numbers in their machine form, binary coding. I will not be talking about this option today.

I will be using the read and write text file classes created earlier to implement a solution for storing data on the first five Presidents of the United States.

The table below summarizes the methods and properties of the classes.

OpenDataFile() Read & Write
CloseDataFile() Read & Write
PushData() Write
PullData() Read
PullAllData() Read
RemoveFile() Write
FileExists() Read
EOF Read







The trick to this format is to use a string buffer and to place the fields at the correct positions. All numeric data has to be saved text which may or may not cause lose of percision. I wrote the following helper functions to solve this buffer manipulation.

The “PackField” helper function packages a variable length string into a fixed one. Any null issues are avoided by appending a empty string at the start of the expression.


The “UnpackField” helper function chops off the field at the start of the string and returns it. The orginal string is modified to remove from the record.


In summary, writing to and reading from fixed formatted text files is very easy. You might bump into this format when exchanging data with clients that use the IBM mainframe.

The table below has started code that you can use in your next Visual Basic (VB) Script.

mod-write-text-file.vbs Write Text File Class
mod-read-text-file.vbs Read Text File Class
tst-write-flat-file.vbs Write Flat File Program
tst-read-flat-file.vbs Read Flat File Program
write-flat.cmd Write Batch File
read-flat.cmd Read Batch File
presidents Presidents Flat File
flat-file-output Read Program Output

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One Thought to “Fixed Formatted Text Files”

  1. magnificent put up, very informative. I wonder why the other specialists of this sector don’t understand this. You should proceed your writing. I’m confident, you have a great readers’ base already!

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