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In this module, I will present and explain a Scratch program named Logical01 . This program illustrates the use of the and , or , and not operators in Scratch. These are called logical operators.

In this module, I will provide an explanation of logical operators and truth tables . Then I will present and explain a Scratch program that illustrates the use of the logical and , or , and not operators when used in conjunction with relational operators. You learned about relational operators in an earlier module.

Finally, I will provide the specifications for two programming projects for you to demonstrate your understanding of what you learned from the first programand from earlier modules. One of the programming projects is relatively difficult requiring an understanding of DeMorgan's theorem .

Copies of all three programs will be posted online for your review (see Resources for the URL) . If you don't find the program using that URL, search the Scratch site for the usernamed dbal .

A real-world example

Logical operators can be confusing at first glance, but perhaps a real world example will help to eliminate some of that confusion. For many years in thiscountry, we have had a movie rating system designed to control the viewing of objectionable content by young people. According to Wikipedia , the R rating means something like the following:

"Restricted - Under 17 requires accompanying parent or adult 17 or older with photo ID"

Formulate this using logical operator concepts

In most cases, this means that a person will be allowed entry into the theatre to view the movie if:

  • The person has the price of admission and is older than 16, or
  • The person has the price of admission and is under 17 and is accompanied by an adult who also has the price of admission and the adult can show a photo ID.

Note the use of the boldface Italicized words or and and in the above example.

The not operator

The not operator is a little more difficult to explain in terms of real world examples. At this point, suffice it to say that the application ofthe not operator causes something that is true to become false and causes something that is false to become true. For example, if someone is older than16, that person is not 16 or younger.

The reality - logic in a formal sense

The reality is that you have been dealing with this kind of logic most of your life. However, unless you had a specific reason to do so, such as being acomputer programmer, a computer engineer, or perhaps an attorney, you may never have thought about it in a formal sense. The time to think about it in a formalsense has arrived.

A sample program named Logical01

A button and s even variables

This program creates a button along with the following seven variables.

A (a slider variable) B (a slider variable)C (a slider variable) D (a slider variable)A<B and C<D not(A<B and C<D) A<B or C<D

The program displays the button and the variables on the Stage and initializes all of the variables to zero when the user clicks the green flag asshown in Image A .

Image a. reduced screen shot of the programmer interface for the program named logical01.

Missing image
Image A. Reduced screen shot of the programmer interface for the program named Logical01.

Questions & Answers

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
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
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
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
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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