<< Chapter < Page Chapter >> Page >
This module explains the Python loop modifiers: else, continue, break,and pass.

Table of contents

Preface

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 have learned

You have learned how to construct while loops, for loops, and if statements in recent modules on control flow in Python. In addition, you recently learned how to create nested loop structures .

What you will learn

In this module, you will learn how to add an else clause to while loops and for loops. In addition, once you start using nested loops, you need to know how to use the loop modifiers: continue and break . Those loop modifiers will be explained in this module.

Finally, this module will make a brief mention of the pass statement, which does nothing. If you need to write code that does nothing, the pass statement is for you.

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: most of the Figures and all of the 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.)

Figures

  • Figure 1 . Output from the code in Listing 1.
  • Figure 2 . Output from the code in Listing 2.
  • Figure 3 . Output from the code in Listing 3.

Listings

  • Listing 1 . Loops with else clauses.
  • Listing 2 . Nested loops with a continue statement.
  • Listing 3 . Nested loops with a break statement.

Discussion and sample code

The else clause

You learned about the else clause on an if statement in an earlier module titled Itse1359-1230-The if Statement .

Loop statements can also have an else clause. The else clause on a for loop is executed when the loop terminates through exhaustion of the elements in the list.The else clause on a while loop is executed when the loop terminates because the condition becomes False . The else clause is not executed when the loop is terminated by a break statement.

I will illustrate the else clause using a program that is similar to the odometer program that you learned about in the earlier module titled Itse1359-1250-Nested Loops . The program is shown in Listing 1 .

Listing 1 . Loops with else clauses.
# Illustrates nested loops with else clauses #---------------------------------------------------------------------------leftDigit = 0 rightDigit = 0#Begin outer while loop while leftDigit<2: leftDigit += 1#Begin for loop for middleDigit in range(1,3):rightDigit = 0 #Begin innermost while loopwhile rightDigit<3: rightDigit += 1print(str(leftDigit) + "-" + str(middleDigit) + "-" + str(rightDigit)) else:print("In else clause on inner while loop") #end inner while loop with else clauseelse: print("In else clause on for loop")#end for loop with else clause else:print("In else clause on outer while loop") #end outer while loop with else clauseprint("Goodbye")

Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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
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
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Berger describes sociologists as concerned with
Mueller Reply
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!





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
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Itse 1359 introduction to scripting languages: python' conversation and receive update notifications?

Ask