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Can also use a variable

Note that I also created a dummy variable in Image E for illustration purposes. Because the shape of a variable block is the same as the shape of thewhite box in the repeat block, you can also drop a variable block into the box. When you do this, the value of the variable will be used to determinehow many times the code in the block will be executed. That number may be different each time the repeat block is executed.

The wait block

Image E also shows a wait block, which can be dragged into the center panel from the Control toolbox. Like the repeat block, the wait block has a white box into which you can either enter a literal value or drop a variable block.

The program will pause for a specified number of seconds (which may be a decimal fraction) each time the wait block is executed. If you enter a literal value into the box, the program will pause for the same amountof time each time the wait block is executed. If you drop a variable block into the box, the length of the pause will be the current value stored inthe variable, which may be different each time the block is executed.

The switch costume block

Finally, Image E shows a purple switch to costume block. This block is available in the purple Looks toolbox when a sprite icon is selected immediately below the stage. However, when the Stage icon is selected, theblock changes to one labeled switch to backdrop . (A discussion of backdrops will be deferred to a future module.)

As you can see, the switch to costume block has a pull-down list that allows you to select a specific costume for the block when you write theprogram. The list contains all of the costumes belonging to the selected sprite. In the case of the default cat that appears for new projects, there are two costumes in the pull-down listbecause the cat has two costumes as shown in Image D .

The program code

The code for this program is shown in Image F .

Image f. program code for the program named forloop01.

Missing image.
Image F. Program code for the program named ForLoop01.

Behavior of the program

When the user clicks the green flag, the cat moves to the center of the stage (the origin of the Cartesian coordinate system) and turns to face the viewer's right. In addition, the cat switches to costume1 (see Image D ) even if that isn't necessary at this point. (Except for switching costumes, you have seen code like this in earlier modules.)

The repeat block

Then the code inside the repeat block shown in Image F is executed 24 times in succession.

During each execution (iteration) of the repeat block, the cat:

  • Moves 10 steps forward.
  • Waits 0.1 second.
  • Switches to costume2.
  • Rotates around its own origin by 15 degrees.
  • Waits an additional 0.1 seconds.
  • Switches back to costume 1.

This causes the cat to appear to walk (in a rather jerky fashion) in a circle (see Image G ) , ending up very close to where it started.

Image g. the cat on the stage.

Missing image.
Image G. The cat on the Stage.

Run the online version

In order to get the full impact of this program, you will either need to create the program yourself or run the online version (see Resources ) .

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
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
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
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Source:  OpenStax, Teaching beginners to code. OpenStax CNX. May 27, 2013 Download for free at http://cnx.org/content/col11498/1.20
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