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Allowable variable names and lengths

Most programming languages have very specific requirements regarding the allowable characters for variable names. I suspect that this is also true ofScratch, but I haven't found that specification anywhere. You will probably be okay as long as you stick with letters, numbers, the underscore character"_", and the hyphen or minus sign "-".

It appears experimentally that the allowable length of the variable name is longer than you would ever want to use so length doesn't seem to be alimitation.

Many programming languages won't allow you to use a numeric character for the first character in a variable name, but that restriction doesn't seem to applyto Scratch. However, since you might later move up to more mainstream languages, you might want to avoid getting into the habit of using numeric characters asthe first character in variable names.

Meaningful variable names

When using Scratch and all other programming languages, you should strive to use variable names that are meaningful. My preference is to begin variable nameswith a lower-case letter, use multiple words in the name where appropriate, and separate the words using a format commonly called camelCase to cause the human eye to separate the words.

(The upper-case characters are analogous to the humps on a camel.)

Here is an example of the camelCase format:

aVariableName

Some people prefer the following format:

A_Variable_Name

I prefer the camelCase format because it is easier to type, requires fewer characters, takes less space, and in my opinion, is just as effective.

Writing the program

Generally speaking, programs are written in Scratch by:

  1. Selecting buttons in the upper-center of Image 1 to expose the programming blocks in the tool boxes associated with each of the categories listed earlier .
  2. Dragging programming blocks from the toolbox in Image 1 to the rightmost pane in Image 1 and snapping those blocks together in groups to form program scripts.
  3. Entering literal numeric values or dragging other blocks and dropping them into text fields with the same shapeto fill out the details of the program.

There are other steps involved in writing a complex program that I didn't include above, but we will get to them later in this collection of modules.Hopefully you already know the physical steps in writing a program as a result of working through some online tutorials.

Although Scratch 2.0 has some new features and a different screen layout, the general procedure for writing a program in Scratch 2.0 isessentially the same as the procedure for writing a program in Scratch 1.4. Thus, the older v1.4 tutorials are still very relevant.

As you can see in Image 1 , this program consists of three scripts in the rightmost pane. Each script contains onetan block and two orange blocks. We already know that orange blocks have to do with data or variables. As you can see from the colors on the left ends of the buttonsin Image 1 , tan blocks are related to Events .

Programming blocks in the Events category

Image 3 shows some of the programming blocks that are available in the Events category. (Scratch 1.4 had tools for the Events category and the Control category combined into a single toolbox.)

Questions & Answers

what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
x+2y-z=7
Sidiki
what is the coefficient of -4×
Mehri Reply
-1
Shedrak
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
Akash
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.
Carole
I'm 13 and I understand it great
AJ
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Atone
hi
Adu
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
Vedant
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
salma
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
Abhi
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
Augustine
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
AJ
how
Sheref
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
hmm
Abhi
is it a question of log
Abhi
🤔.
Abhi
I rally confuse this number And equations too I need exactly help
salma
But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
salma
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
hi
salma
hi
Ayuba
Hello
opoku
hi
Ali
greetings from Iran
Ali
salut. from Algeria
Bach
hi
Nharnhar
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
Shanjida
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
s.
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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