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Image i. final screen output from the program named repeatuntil01.

Missing image.
Image I. Final screen output from the program named RepeatUntil01.

Doesn't have to be the last block in the script

Unlike the forever block, it is possible to connect another block to the bottom of a repeat until block. Therefore, it is not necessary for a repeat until block to be the last block in a script. This means that a program can continue to execute a repeat until block until a specified condition becomes true, and then move on to execute additional code.

This structure is more similar to the structures typically found in modern programming languages than are the structures required by the forever block. However, most modern programming structures repeat something while a condition is true instead of repeating it until a condition becomes true.

Available online

At the real risk of becoming really boring, I will tell you again that you can copy the code from Image H and run your own copy of the program. Also, the program has been posted online so that you can run it from there. (See the link to the online version in Resources .)

The loop blocks

The three blocks shown in Image J are the only blocks available to create loop structures in Scratch version 2.0.

(The forever if block that was available in v1.4 is no longer available in v2.0. However, its functionality can approximated by embedding an if block in a forever block.)

Image j. blocks that can be used to create loop structures in v2.0.

Missing image.
Image J. Blocks that can be used to create loop structures in v2.0.

In this and the previous program, I have provided discussions and sample programs using the three blocks in Image J as well as a discussion and sample program for a forever block with an embedded if block.

Run the programs

I encourage you to use the information provided above to write and run these three programs. Experiment with the code, making changes, and observing theresults of your changes. Make certain that you can explain why your changes behave as they do.

Just for fun, see if you can cause the cat to change color as it marches around in the circle.

I also encourage you to write the program described below.

Student programming project

Write a program named ForeverLoop03 that is very similar to the program named ForeverLoop01 . Once again, the cat marches in a circle when the user holds down the space bar (after first clicking the green flag) . However, this program also produces an audio output that is a nice drumbeat andthe cat marches in synchronism with the drumbeat.

My version of this program has been posted online so that you can run it from there. (See Resources for the link to the online version.)

Because of the speed of my computer and the speed of my Internet connection, the synchronization of the drumbeat and the animation in v2.0 is notas good as it was when running the program locally under v1.4. Losing the ability to run Scratch programs locally is one disadvantage of the changes thatwere made in v2.0.

Summary

In this module, I presented and explained three Scratch programs. One program uses a forever block in conjunction with an embedded if block to cause a sprite to move in a small circle whilethe space bar is pressed. I explained that it is not possible to connect another block to the bottom of a forever block. Therefore, if you use a forever block, it must be the last block in the script in which it is contained.

Questions & Answers

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
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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit 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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