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Four variables

The leftmost panel shows that four variables have been created. Because you can't read the names of those variables, I will list them here:

  • LeftOperand
  • RightOperand
  • Sum
  • Diff

You can barely see that the checkboxes next to all four variables have been checked. As you learned in an earlier module, checking this box causes avariable to be displayed in the white Stage area on the right. Thus you can see all four variables being displayed in the upper left corner of theStage.

A button

Skipping to the area immediately below the Stage, you can (almost) see that a button has been added to the program. That button has been selected in Image 1 , making it possible to drag blocks into the center panel that controls thebehavior of the button.

Two scripts in the center panel

Although you can't read the details in Image 1 , you can see that there are two scripts showing in the center panel. (I will show you a full-size screen shot of the center panel later in Image 2 .)

For now, suffice it to say that the top script initializes the values stored in all four variables when theuser clicks the green flag in the upper right of Image 1 . The bottom script in the center panel defines the behavior of the program when the userclicks the button in the Stage area.

Variables with sliders

If you look carefully, you can tell that the top two variables that are displayed in the Stage area look different from the bottom two variables.This is because a slider has been assigned to each of the top two variables (see Image 5 ) . This makes it possible for the user to manually set the values stored in each of these two variables.

How to create a slider

To create a slider for a variable, right click on the display of the variable in the Stage area and select slider in the popup menu that appears.

Once you have caused a slider to appear with the variable display, you can right-click on the variable display again and select set slider min and max in the popup menu to specify the range of the slider. This will cause asimple dialog box to appear into which you can enter the minimum value and the maximum value and then click an OK button. In this program, I have bothsliders set to a minimum value of -10 and a maximum value of +10.

Full-size view of the center panel

Image 2 shows a full-size view of the center panel after having selected the button icon in the area immediately below the Stage in Image 1 .

Image 2. full-size view of the center panel.

Missing image.
Image 2. Full-size view of the center panel.

Initialize the variable values to zero

As I mentioned earlier, the top script in Image 2 sets the value of each of the four variables to zero when the user clicks the green flag. The codein that script should be completely familiar to you by now and no explanation should be necessary.

Define the behavior of the button

The bottom script in Image 2 defines the behavior of the program when the button is clicked. Basically, that code says to set the value of thevariable named Sum to the sum of the contents of the two variables named LeftOperand and RightOperand and to set the value of the variable named Diff to the value of the left operand minus the value of the right operand.

Questions & Answers

Need help solving this problem (2/7)^-2
Simone Reply
what is the coefficient of -4×
Mehri Reply
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
I'm 13 and I understand it great
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
I rally confuse this number And equations too I need exactly help
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Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
greetings from Iran
salut. from Algeria
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris 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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