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Eventually, either our stillHungry variable will be set to false, or the cookie box will become empty. At that point, the test will return false. Wewill terminate the loop and will stop eating cookies even though we might still be hungry for more cookies.

The while and for keywords

Most modern programming languages use the keywords while and for to implement loop structures such as this and you will see those keywords in useonce you get to Java, C++, C#, etc.

However, Scratch does not use those keywords to implement loops. Regardless, when I present pseudocode examples to explain Scratchprograms, I will continue to use while and for to get you accustomed to that terminology.

Preview

In this module, I will present and explain the following two Scratch programs:

  • ForLoop01 - This program illustrates the Scratch equivalent of a for loop (or something similar to a for loop) in other languages. In Scratch, it is called a repeat loop.
  • ForLoop02 - This program also illustrates the Scratch equivalent of a for loop in other languages. However, this program takes a different approach to specifying the number of times that the code in theloop is executed.

In addition, I will provide the specifications for a student-programming project for you to demonstrate your understanding of what you learned from thetwo programs listed above. In addition, this programming project will require you to do some independent research into the manner in which Scratch sprites cancommunicate with one another.

Discussion and sample code

The program named ForLoop01

This program illustrates the Scratch equivalent of a for loop (or something similar to a for loop) in other programming languages. In Scratch, it is called a repeat .

Why do I keep saying "something similar to a for loop?" The reason is that a for loop in other programming languages has many facets. Therepeat loop in Scratch is much more restricted than a for loop in those other languages.

This program places a cat sprite having two costumes on the stage. When the user clicks the green flag, code is executed that is equivalent to thepseudocode shown in Image C .

Image c. pseudocode for the program named forloop01.

Initialize cat position, orientation, and costume for(count = 0;count<24,count = count + 1){Cat moves ten steps forward. Cat waits 0.1 secondCat switches to costume #2 Cat turns 15 degreesCat waits 0.1 second Cat switches back to costume #1}//end for loop
Image C. Pseudocode for the program named ForLoop01.

Why set count to 0 ?

Most modern programming languages typically start counting with 0 instead of 1, but that is not necessarily the case with Scratch. You will learn more aboutthat when you get into Java, C++, C#, etc.

Purpose of the pseudocode

My purpose in providing the pseudocode is to help you better understand the Scratch code that follows. I am also preparing you for the use of otherprogramming languages later. I recommend that you compare the pseudocode with the Scratch code, and compareboth of them with what you see when you run the program.

What's new in this Scratch program?

This program contains several new code blocks that haven't been used in previous modules:

  • The switch costume block
  • The repeat block
  • The wait block

The only one of these blocks that I would put in the programming fundamentals category is the repeat block, and even the syntax of that block is quite a bit different from other modern programming languages.However, the other blocks are some of the things that cause Scratch programming to be fun, so I will use and explain such blocks as we go along.My only caution is that you should not expect to find those commands in other programming languages, at least not using the same syntax.

Questions & Answers

show that the set of all natural number form semi group under the composition of addition
Nikhil Reply
what is the meaning
Dominic
explain and give four Example hyperbolic function
Lukman Reply
_3_2_1
felecia
⅗ ⅔½
felecia
_½+⅔-¾
felecia
The denominator of a certain fraction is 9 more than the numerator. If 6 is added to both terms of the fraction, the value of the fraction becomes 2/3. Find the original fraction. 2. The sum of the least and greatest of 3 consecutive integers is 60. What are the valu
SABAL Reply
1. x + 6 2 -------------- = _ x + 9 + 6 3 x + 6 3 ----------- x -- (cross multiply) x + 15 2 3(x + 6) = 2(x + 15) 3x + 18 = 2x + 30 (-2x from both) x + 18 = 30 (-18 from both) x = 12 Test: 12 + 6 18 2 -------------- = --- = --- 12 + 9 + 6 27 3
Pawel
2. (x) + (x + 2) = 60 2x + 2 = 60 2x = 58 x = 29 29, 30, & 31
Pawel
ok
Ifeanyi
on number 2 question How did you got 2x +2
Ifeanyi
combine like terms. x + x + 2 is same as 2x + 2
Pawel
x*x=2
felecia
2+2x=
felecia
×/×+9+6/1
Debbie
Q2 x+(x+2)+(x+4)=60 3x+6=60 3x+6-6=60-6 3x=54 3x/3=54/3 x=18 :. The numbers are 18,20 and 22
Naagmenkoma
Mark and Don are planning to sell each of their marble collections at a garage sale. If Don has 1 more than 3 times the number of marbles Mark has, how many does each boy have to sell if the total number of marbles is 113?
mariel Reply
Mark = x,. Don = 3x + 1 x + 3x + 1 = 113 4x = 112, x = 28 Mark = 28, Don = 85, 28 + 85 = 113
Pawel
how do I set up the problem?
Harshika Reply
what is a solution set?
Harshika
find the subring of gaussian integers?
Rofiqul
hello, I am happy to help!
Shirley Reply
please can go further on polynomials quadratic
Abdullahi
hi mam
Mark
I need quadratic equation link to Alpa Beta
Abdullahi Reply
find the value of 2x=32
Felix Reply
divide by 2 on each side of the equal sign to solve for x
corri
X=16
Michael
Want to review on complex number 1.What are complex number 2.How to solve complex number problems.
Beyan
yes i wantt to review
Mark
16
Makan
x=16
Makan
use the y -intercept and slope to sketch the graph of the equation y=6x
Only Reply
how do we prove the quadratic formular
Seidu Reply
please help me prove quadratic formula
Darius
hello, if you have a question about Algebra 2. I may be able to help. I am an Algebra 2 Teacher
Shirley Reply
thank you help me with how to prove the quadratic equation
Seidu
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Opoku
what is math number
Tric Reply
4
Trista
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
can you teacch how to solve that🙏
Mark
Solve for the first variable in one of the equations, then substitute the result into the other equation. Point For: (6111,4111,−411)(6111,4111,-411) Equation Form: x=6111,y=4111,z=−411x=6111,y=4111,z=-411
Brenna
(61/11,41/11,−4/11)
Brenna
x=61/11 y=41/11 z=−4/11 x=61/11 y=41/11 z=-4/11
Brenna
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
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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