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The syntax of the call to the print function with two parameters in Listing 3 is probably different from what you have seen in my previous modules. By default, the print function terminates each output line with a newline . Because the lines of text in the file already contain a newline, without the second parametershown in Listing 3 , the output shown in Figure 1 would be double-spaced. The inclusion of the second parameter in the call to the print function in Listing 3 prevents the print function from inserting an extra newline and inserts an empty string instead.

Append more text to the file

The code in Listing 4 begins by printing a blank line to cause the output shown in Figure 3 to be more readable.

Then the code in Listing 4

  • re-opens the file for appending,
  • writes two additional text lines into the file, and
  • closes the file.
Listing 4 . Append more text to the file.
print()#blank line to separate the output text #Append some text to the file.#Open the file object for appending. theFile = open("SampleTextFile.txt","a")#Append two more lines of text to the file. theFile.write("First appended line.\n")theFile.write("Second appended line.\n") #Close the filetheFile.close()

Read and print the file contents with a while loop

The readline method of a file object will read and return the next line from the file. An empty string is returned whenthe end of file is encountered. (There are some subtle ramifications that you can learn about at File Objects .)

The code in Listing 5 uses the readline method in a while loop to read and print each line of text in the file.

Listing 5 . Read and print the file contents with a while loop.
#Open the file object in default read mode. theFile = open("SampleTextFile.txt")#Read and print the lines of text using a different approach. line = theFile.readline()print(line,end='') while line != "":line = theFile.readline() print(line,end='')#Close the file theFile.close()

Figure 2 shows the output produced by the code in Listing 5 .

Figure 2 . Output from the code in Listing 5.
This is a sample text file. Second line of text.Third line. Fourth line.Last line. First appended line.Second appended line.

If you compare Figure 2 with Figure 1 , you will see that the two lines of text that were appended by the code in Listing 4 are shown in Figure 2 .

Run the program

I encourage you to copy the code from Listing 6 . Execute the code and confirm that you get the same results as those shown in Figure 3 . Experiment with the code, making changes, and observing the results of your changes. Make certain that youcan explain why your changes behave as they do.

Complete program listing

A complete listing of the program discussed in this module is provided in Listing 6 . The output produced by this program is shown in Figure 3 .

Listing 6 . Complete program listing.

# Illustrates how to write, read, and append to a text file. #---------------------------------------------------------------------------#Open a file object for writing. theFile = open("SampleTextFile.txt","w")#Write several lines of text to the file. Note the requirement to explicitly #provide the newline at the end of each line of text.theFile.write("This is a sample text file.\n") theFile.write("Second line of text.\n")theFile.write("Third line.\n") theFile.write("Fourth line.\n")theFile.write("Last line.\n") #Be sure to close the filetheFile.close() #Open the file object in read mode. Note that the "r" mode is the default#but it is shown here for clarity. theFile = open("SampleTextFile.txt","r")#Read and print the lines of text. for line in theFile:print(line,end='') #Close the filetheFile.close() print()#blank line to separate the output text#Append some text to the file. #Open the file object for appending.theFile = open("SampleTextFile.txt","a") #Append two more lines of text to the file.theFile.write("First appended line.\n") theFile.write("Second appended line.\n")#Close the file theFile.close()#Open the file object in default read mode. theFile = open("SampleTextFile.txt")#Read and print the lines of text using a different approach. line = theFile.readline()print(line,end='') while line != "":line = theFile.readline() print(line,end='')#Close the file theFile.close()
Figure 3 . Output produced by the code in Listing 6.
This is a sample text file. Second line of text.Third line. Fourth line.Last line. This is a sample text file.Second line of text. Third line.Fourth line. Last line.First appended line.

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Itse1359-1510-Reading and Writing Text Files
  • File: Itse1359-1510.htm
  • Published: 10/28/14
  • Revised: 02/08/16
Disclaimers:

Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.

I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.

In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.

Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.

-end-

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
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.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
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Cied
what is biological synthesis of nanoparticles
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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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