<< Chapter < Page Chapter >> Page >

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.


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

Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Teaching beginners to code. OpenStax CNX. May 27, 2013 Download for free at http://cnx.org/content/col11498/1.20
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Teaching beginners to code' conversation and receive update notifications?