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The procedure for doing that is as follows:

  • Open the code visualizer .
  • Copy the example program code into the online text editor .
  • Select Python 3.3 in the pull-down list.
  • Click the button labeled Visualize Execution .
  • Use the Forward and Back buttons to step forward and backward through your code, one instruction at a time,while observing the positions of the red and green arrows and observing the information that appears on the screen to the right of the code window.

Discussion and sample code

The earlier module titled Itse1359-1060-Syntax in this book presented and explained the two Pythonprograms shown in Listing 1 and Listing 2 . I will illustrate the use of the code visualizer with this pair of sample programs.

Listing 1. A sample program with proper indentation.
A = 3 B = 4if B>A: print(A) # begin groupprint(B) print(A + B) # end groupA = 6 # not part of above group print(A)
Listing 2. Another sample program with proper indentation.
A = 4 B = 3if B>A: print(A) # begin groupprint(B) print(A + B) # end groupA = 6 # not part of above group print(A)

Open the online text editor

When you first open the online text editor , a portion of the screen will look like Figure 1 .

Figure 1. The online text editor.

missing image

The blank portion at the top of Figure 1 is the text editor portion of the screen.

Three drop-down boxes

There are three drop-down boxes at the bottom of Figure 1 that allow you to selectdifferent options. The different options in these boxes control the manner in which the output information is presented as youstep through the program. In some cases, you might want to step through the same program more than once with different sets of options selected.

Beginning the visualization process

Figure 2 shows the result of pasting the code from Listing 1 into the text editor and pressing the button in Figure 1 labeled Visualize Execution .

Figure 2. Beginning the visualization process.

missing image

The red and green arrows

As indicated by the key in the bottom left corner of Figure 2 , two arrows will appear next to the code as you step through the code. A redarrow shows the instruction that will be executed the next time you press the Forward button. (Pressing the Back button moves the red arrowback one step.) The green arrow shows the instruction that was most recently executed. (The green arrow isn't visible in Figure 2 because it is underneath the red arrow at the beginning.)

Output following three presses of the Forward button

Figure 3 shows the result of pressing the Forward button three times.

Figure 3. Output following three presses of the Forward button.

missing image

We see from the green arrow on the left that the relational test in the if statement was the most recently executed instruction.

We see on the right that the variables named A and B contain references (pointers) to objects of type int containing values of 3 and 4 respectively.

Because B is greater than A , the relational test in the if statement (pointed to by the green arrow) returned true when that statement was executed. This means that the threestatements in the indented block following the if statement will be executed. The red arrow points to the first statement in the indented blockmeaning that it will be executed the next time the user presses the Forward button.

Questions & Answers

how does Neisseria cause meningitis
Nyibol Reply
what is microbiologist
Muhammad Reply
what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
Ntefuni Reply
What is microbiology
Mercy Reply
studies of microbes
Louisiaste
when we takee the specimen which lumbar,spin,
Ziyad Reply
How bacteria create energy to survive?
Muhamad Reply
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
Louisiaste
what is sporadic nd endemic, epidemic
Aminu Reply
the significance of food webs for disease transmission
Abreham
food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
Mark
explain assimilatory nitrate reduction
Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
Shu Reply
Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
Mark
what is cell
faisal Reply
cell is the smallest unit of life
Fauziya
cell is the smallest unit of life
Akanni
ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
Musa
what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
Lubega
Heyy Lubega hussein where are u from?
_Adnan
en français
Adama
which site have a normal flora
ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
Safaa
skin
Asiina
skin,Oral,Nasal,GIt
Sadik
How can Commensal can Bacteria change into pathogen?
Sadik
How can Commensal Bacteria change into pathogen?
Sadik
all
Tesfaye
by fussion
Asiina
what are the advantages of normal Flora to the host
Micheal
what are the ways of control and prevention of nosocomial infection in the hospital
Micheal
what is inflammation
Shelly Reply
part of a tissue or an organ being wounded or bruised.
Wilfred
what term is used to name and classify microorganisms?
Micheal Reply
Binomial nomenclature
adeolu
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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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