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To have a clear understanding of computer science terms such as those that follow, we recommend lookingat Wikipedia
scope
within a program, it is a region where a variable can be accessed and its valuemodified
global scope
defined outside the methods setup() and draw(), the variable is visible andusable anywhere in the program
local scope
defined within a code block or a function, the variable takes values that arelocal to the block or function, and any values taken by a global variable having the same name are ignored.

Array declaration and allocation

int[] arrayDiInteri = new int[10];
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Programming structures

Conditional instructions

  • if: if (i == NMAX) { println("finished");} else {i++; }

Iterations

  • while: int i = 0; //integer counter while (i < 10) { //write numbers between 0 and 9 println("i = "+ i); i++; }
  • for: for (int i = 0; i < 10; i++) { //write numbers between 0 and 9 println("i = "+ i); }

Initializing a table of random numbers

int MAX = 10; float[] tabella = new float[MAX]; for (int i = 0; i < MAX; i++) tabella[i] = random(1); //random numbers between 0 and 1 println(tabella.length + " elements:"); println(tabella);
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Functions

Functions allow a modular approach to programming. In Processing, in the intermediate programming mode, we can define functions other than setup() and draw() , usable from within setup() and draw() .

Example of function

int raddoppia(int i) { return 2*i; }
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A function is characterized by the entities (with reference to the example ) :

  • return type ( int )
  • name ( raddoppia )
  • parameters ( i )
  • body ( return 2*i )

Objects and classes

A class is defined by a set of data and functions. An object is an instance of a class. Vice versa, a class is the abstractdescription of a set of objects.

For an introduction to the concepts of object and class see Objects and Classes .

Example of class

Dot myDot; void setup() { size(300,20); colorMode(RGB,255,255,255,100); color tempcolor = color(255,0,0); myDot = new Dot(tempcolor,0); } void draw() { background(0); myDot.draw(10); } class Dot { color colore; int posizione; //****CONSTRUCTOR*****// Dot(color c_, int xp) { colore = c_; posizione = xp; } void draw (int ypos) { rectMode(CENTER); fill(colore); rect(posizione,ypos,20,10); } }
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A class is characterized by the following entities (with reference to the example ) :

  • name ( Dot )
  • data ( colore, posizione )
  • constructor ( Dot() )
  • functions (or methods, draw() )

An object (instance of a class) is declared in the same way as we declare a variable, but we have to allocate a space for it(as we did for the arrays) by means of its constructor (with reference to the example ).

  • Declaration: ( Dot myDot; )
  • Allocation: ( myDot = new Dot(tempcolor,0) )
  • Use: ( myDot.draw(10); )

For a quick introduction to the Java syntax see Java Syntax Primer

With the following draw() method we want to paint the window background with a gray whose intensity depends on the horizontal position of themouse pointer. void draw() { background((mouseX/100)*255);} However, the code does not do what it is expected to do. Why?

The variable mouseX is of int type, and the division it is subject to is of the integer type. It is necessary to perform a type casting from int to float by means of the instruction (float)mouseX .

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Questions & Answers

what is mutation
Janga Reply
what is a cell
Sifune Reply
how is urine form
Sifune
what is antagonism?
mahase Reply
classification of plants, gymnosperm features.
Linsy Reply
what is the features of gymnosperm
Linsy
how many types of solid did we have
Samuel Reply
what is an ionic bond
Samuel
What is Atoms
Daprince Reply
what is fallopian tube
Merolyn
what is bladder
Merolyn
what's bulbourethral gland
Eduek Reply
urine is formed in the nephron of the renal medulla in the kidney. It starts from filtration, then selective reabsorption and finally secretion
onuoha Reply
State the evolution relation and relevance between endoplasmic reticulum and cytoskeleton as it relates to cell.
Jeremiah
what is heart
Konadu Reply
how is urine formed in human
Konadu
how is urine formed in human
Rahma
what is the diference between a cavity and a canal
Pelagie Reply
what is the causative agent of malaria
Diamond
malaria is caused by an insect called mosquito.
Naomi
Malaria is cause by female anopheles mosquito
Isaac
Malaria is caused by plasmodium Female anopheles mosquitoe is d carrier
Olalekan
a canal is more needed in a root but a cavity is a bad effect
Commander
what are pathogens
Don Reply
In biology, a pathogen (Greek: πάθος pathos "suffering", "passion" and -γενής -genēs "producer of") in the oldest and broadest sense, is anything that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term pathogen came into use in the 1880s.[1][2
Zainab
A virus
Commander
Definition of respiration
Muhsin Reply
respiration is the process in which we breath in oxygen and breath out carbon dioxide
Achor
how are lungs work
Commander
where does digestion begins
Achiri Reply
in the mouth
EZEKIEL
what are the functions of follicle stimulating harmones?
Rashima Reply
stimulates the follicle to release the mature ovum into the oviduct
Davonte
what are the functions of Endocrine and pituitary gland
Chinaza
endocrine secrete hormone and regulate body process
Achor
while pituitary gland is an example of endocrine system and it's found in the Brain
Achor
what's biology?
Egbodo Reply
Biology is the study of living organisms, divided into many specialized field that cover their morphology, physiology,anatomy, behaviour,origin and distribution.
Lisah
biology is the study of life.
Alfreda
Biology is the study of how living organisms live and survive in a specific environment
Sifune
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Source:  OpenStax, Media processing in processing. OpenStax CNX. Nov 10, 2010 Download for free at http://cnx.org/content/col10268/1.14
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