<< Chapter < Page Chapter >> Page >

As a binary operator, the minus character causes its right operand to be subtracted from its left operand. For example, the third statement belowsubtracts the variable y from the variable x and assigns the result of the subtraction to the variable z . After the third statement is executed, the variable z contains the value 1.

int x = 6;

int y = 5;

int z = x - y;

The minus character as a unary operator

As a unary operator, the minus character causes the algebraic sign of the right operand to be changed. For example, the second statement belowcauses a value of -5 to be assigned to (stored in) the variable x .

int y = 5;

int x = -y;

Binary operators use infix notation

To keep you abreast of the current jargon, binary operators in Scratch always use infix notation. This means that the operator appears between its operands.

Some other programming languages have unary operators that use prefix notation and postfix notation. For prefix notation, the operator appears before (to the left of) its operand. For postfix notation, the operator appears after (to the right of) its operand.

General behavior of an operator

As a result of performing the specified action, an operator can be said to return a value (or evaluate to a value) of a given type. The type of value returned depends on the operator and the type of the operands.

To evaluate to a value: To evaluate to a value means that after the action is performed, the operator and its operands are effectively replacedin the expression by the value that is returned.

Operator categories

There are many different kinds of operators. Therefore, the easiest way to study them is to divide them into categories such as the following

  • arithmetic
  • relational
  • logical
  • bitwise
  • assignment

This module will concentrate on arithmetic operators. Future modules will deal with other kinds of operators.


In this module, I will present and explain a Scratch program named Arithmetic01 . This program illustrates the use of the following arithmetic operators (see Image 4 ):

  • + (addition)
  • - (subtraction)

Variables with the following names are created and displayed on the screen (see Image 5 ):

  • LeftOperand - has a slider
  • RightOperand - has a slider
  • Sum
  • Diff

In addition, a button is displayed on the screen.

The user adjusts the values of the LeftOperand and RightOperand variables with a pair of sliders. When the user clicks the button, the variablenamed Sum displays the sum of the values of the left and right operands. The variable named Diff displays the result of subtracting the right operand from the left operand.

Discussion and sample code

I'm going to walk you through the steps required to develop this program, being brief on those things that you already know about and being more verboseon the new material.

To begin with, Image 1 shows a reduced screen shot of the user interface.

Image 1. reduced screen shot of arithmetic01 in operation.

Missing image.
Image 1. Reduced screen shot of Arithmetic01 in operation.

I realize that Image 1 lacks detail due to the requirement to reduce the size of the screen shot for publication in this format, but there are someaspects of Image 1 that are worth noting. I will go from left to right in Image 1 making comments.

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
Privacy Information Security Software Version 1.1a
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?