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This module introduces control flow in general and explains the use of the while loop in Python.

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

Earlier modules in this collection have included instruction on the following topics:

  • numbers
  • variables
  • identifiers
  • strings
  • scripts
  • lists
  • tuples

This has prepared you to use Python as a very fancy desk calculator.

What you will learn

The next step in learning to program with Python is to learn how to apply repetition, modularity, and decision logic to your scripts. This is oftenreferred to in computer jargon as control flow .

This module introduces control flow in general and explains the use of the while loop in Python as an example of control flow .

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 script in Listing 1.
  • Figure 2 . Output from the script in Listing 2.
  • Figure 3 . Visualization of the program.

Listings

  • Listing 1 . Typical script from earlier modules.
  • Listing 2 . Use a while loop to manipulate a list.

General background information

A typical script in the earlier modules looked something like the one shown in Listing 1 .

Listing 1 . Typical script from earlier modules.
# Illustrates extracting a # list element and extracting# elements from a nested list ##------------------------------- print("Create and print a list")listA = [100,200,300,400,500] print(listA)print("Original length is:") print(len(listA))print("Replace an element") listA[2]= [2,4,8,16,32,64] print("Print the modified list")print(listA) print("Modified length is:")print(len(listA)) print("Extract and display each")print(" element in the list") print(listA[0]) print(listA[1]) print(listA[2]) print(listA[3]) print(listA[4]) print("Extract and display each")print(" element in nested list") print(listA[2][0])print(listA[2][1]) print(listA[2][2])print(listA[2][3]) print(listA[2][4])print(listA[2][5])

The output produced by the script in Listing 1 is shown in Figure 1 .

Questions & Answers

Ayele, K., 2003. Introductory Economics, 3rd ed., Addis Ababa.
Widad Reply
can you send the book attached ?
Ariel
?
Ariel
What is economics
Widad Reply
the study of how humans make choices under conditions of scarcity
AI-Robot
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn Reply
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn
what is ecnomics
Jan Reply
this is the study of how the society manages it's scarce resources
Belonwu
what is macroeconomic
John Reply
macroeconomic is the branch of economics which studies actions, scale, activities and behaviour of the aggregate economy as a whole.
husaini
etc
husaini
difference between firm and industry
husaini Reply
what's the difference between a firm and an industry
Abdul
firm is the unit which transform inputs to output where as industry contain combination of firms with similar production 😅😅
Abdulraufu
Suppose the demand function that a firm faces shifted from Qd  120 3P to Qd  90  3P and the supply function has shifted from QS  20  2P to QS 10  2P . a) Find the effect of this change on price and quantity. b) Which of the changes in demand and supply is higher?
Toofiq Reply
explain standard reason why economic is a science
innocent Reply
factors influencing supply
Petrus Reply
what is economic.
Milan Reply
scares means__________________ends resources. unlimited
Jan
economics is a science that studies human behaviour as a relationship b/w ends and scares means which have alternative uses
Jan
calculate the profit maximizing for demand and supply
Zarshad Reply
Why qualify 28 supplies
Milan
what are explicit costs
Nomsa Reply
out-of-pocket costs for a firm, for example, payments for wages and salaries, rent, or materials
AI-Robot
concepts of supply in microeconomics
David Reply
economic overview notes
Amahle Reply
identify a demand and a supply curve
Salome Reply
i don't know
Parul
there's a difference
Aryan
Demand curve shows that how supply and others conditions affect on demand of a particular thing and what percent demand increase whith increase of supply of goods
Israr
Hi Sir please how do u calculate Cross elastic demand and income elastic demand?
Abari
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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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