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A variable is a placeholder for a value. Variables Variables are used for storing values. In Java, variables need to be defined with a data-type, to define its storage space requirements. The name of the variable must start with a letter, but it may contain numbers within the name. In processing, variable names are case-sensitive.

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// variable Declaration 
int x1 = 15; // an integer i.e a whole number 
float valF = 0.323; // a floating point number i.e a numbers with a decimal point
boolean bFlag = false; // a true or false value i.e a single bit value
String message = "hallo 1"; // a collection of characters 
char character = 'g'; // a siglesingle character. Note the different quotation marks
 
String msg1 = new String("hallo 2");
 
println(x1);
println(valF);
println(bFlag);
println(message);
println(character);
println(msg1);

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int length1 = 150;
int length2 = 200;
 
size(300,300); // define window size 
background(0); // define background colour
stroke(255,255,255); // define line colour
 
line(100,10,100,length1); // draw a line 
line(150,10,150,length2);
line(200,10,200,250);
 
fill(0,0,0); // fill colour
strokeWeight(5); // line thickness 
ellipse(100,length1,50,50); // draw an ellipse
ellipse(150,length2,50,50); // draw an ellipse
noFill(); // turn off fill
ellipse(200,250,50,50); // draw an ellipse

Primitive Data Types and Memory

Each kind of variable (it's data type) has an allocated amount of memory, which is enough to store a particular range of values. 

Operators 

An operator is a symbol that tells the computer to perform a particular arithmetic math or logic operation. Some of the most common operators are:

+ Addition

/ DevisionDivision

- Subtraction

* Multiplacation Multiplication 

These you already know but there are some very useful arithmetic operators you may not have seen in the following example:

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