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You will learn how to read, write, and append to text files using Python in this module.

Table of contents


This module is one in a collection of modules on Python designed for teaching ITSE 1359 Introduction to Scripting Languages: Python at Austin Community College in Austin, TX.

What you will learn

You will learn how to read, write, and append to text files using Python in this module.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figuresand the Listings while you are reading about them.

(Note to blind and visually impaired students: all of the Figures and Listings inthis module are presented in plain text format and should be accessible using an audio screen reader or a braille display. Note however that the requiredindentation may not be properly represented by an audio screen reader.)


  • Figure 1 . Output from the code in Listing 3.
  • Figure 2 . Output from the code in Listing 5.
  • Figure 3 . Output produced by the code in Listing 6.


  • Listing 1 . Open a text file for writing.
  • Listing 2 . Write text and close the file.
  • Listing 3 . Read and print the file contents with a for loop.
  • Listing 4 . Append more text to the file.
  • Listing 5 . Read and print the file contents with a while loop.
  • Listing 6 . Complete program listing.

General background information

From time to time you may need to read, write, or append to files. I will present and explain a relatively simple program in this module that will get youstarted down that path. However, this module is not intended to be a comprehensive tutorial on file i/o. Instead, I will refer you to other onlineresources for more information if and when you need it. The following web sites provide important information in this regard:

Discussion and sample code

The program that I will present and explain in this module begins by writing a text file named "SampleTextFile.txt" into the current directory and populating it with five lines of text. If a file already exist havingthat name in the current directory, it will be overwritten by the new file.

Then the program uses a for loop as an iterator to read and print each line of text from the file.

After that, the program appends two additional lines of text to the file and uses a while loop to read and print the seven lines of text from the file.

A complete listing of the program is provided in Listing 6 . The output from the program is shown in Figure 3 . As usual, I will break the program down and explain it in fragments. The first fragment is shown in Listing 1 .

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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