programming-for-dummies

260
Storing Data in Text Files
The “other” universal file format
The biggest drawback with text files is that they
can’t contain any formatting information. So if
you need to transfer a word processor document
from an ancient Atari ST computer to a
modern Macintosh computer, you lose all formatting
in that document.
To prevent this problem, computer scientists
created a universal file format that can retain
both data and formatting. This new file format,
XML (Extensible Markup Language), contains
both data and instructions for how to display
the data. For example, the sentence “This is the
text you would actually see” looks like this in an
XML file:
This is the text you
would actually see
Essentially, an XML file is just a text file with formatting
instructions or tags that define the
appearance of data. Because XML files are
text files, any computer can read them. To fully
read an XML file, a computer needs a special
program — an XML parser — which not only
reads the data but also translates the XML formatting
tags that tell the computer how to display
that data.
To create a universal file format for word
processor documents, spreadsheets, databases,
and presentation files, computer scientists
have created a new file format, based on
XML — the OpenDocument standard. The main
idea behind this OpenDocument standard is to
define a universal file format that retains both
data and formatting commonly found in word
processors, spreadsheets, databases, and
presentation program files. Unlike proprietary
file formats, which a single company can control,
the OpenDocument standard is freely
available to anyone.
The OpenDocument file format has even gained
the support of many governments, which want
to insure that people can still read and edit their
files no matter what computer or software they
may be using in the future. If you store important
files in a proprietary file format, such as
Microsoft Word or Microsoft Access, there’s a
chance that programs in the future won’t know
how to open those files, which means your data
could potentially be lost forever. By using the
OpenDocument standard, your data can remain
accessible forever (or at least until computer
scientists create another “universal” file format).
However, to identify data that should logically be lumped together, programs,
such as databases and spreadsheets, offer the option of saving text
files as either
✦ A comma-delimited text file (also known as CSV or Comma Separated
Values) simply divides text into logical chunks, such as
Joe Smith, 123 Main Street, New York, NY, 10012
✦ A tab-delimited text file divides text by tabs (spaces), like this:
Joe Smith 123 Main Street New York NY 10012