Hello Processing - Vula

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An Introduction To Programming With Processing The typical “Hello World” program is many a programmers first attempt at coding. If your console window has the phrase “Hello World” printed in it, congratulations you've successfully completed the Hello World 1.0 program! Like I said earlier, don't expect to be impressed right away, building a more useful program is going to take a little more practice. Nonetheless let's have a look at what is going on here. Firstly you'll notice that the text editor has formatted the text we input in different colors. The colors denote specific meanings in Processing, for example in our Hello World 1.0 program: Orange Orange is used to identify a command. Black Black identifies syntax formatting characters such as parenthesis and a statement terminator. Blue Blue identifies a string of data. Hello World Program 1.0 46
An Introduction To Programming With Processing IDE's such as the PDE that use syntax highlighting make reading code easier to decipher and once you get familiar with what the colors represent you'll find yourself separating the code you are reading into smaller manageable chunks by identifying the colors that serve specific functions. We refer to the sentence typed in the text editor as a statement. Statements are easy to identify because they always end with a semi-colon and not with a period (like in English). Our entire Hello World 1.0 program consists of only one statement which in itself consists of only one command. Processing is a case sensitive language so it is very important that when you type a command you do not mix it's casing because println() and printLn() will not yield the same results, in fact the latter will cause an error. The println() function println() is a special type of command called a function. Sometimes a function is also referred to as a subroutine so how the term is used from one language to another may vary but regardless of what you call it the purpose of a function is generally the same in any programming language, a portion of code (usually a single word followed immediately with parenthesis) that exists within a larger body of code (in our case this could be the sketch we are creating) and performs a specific task within the context of the program but is also independent of the program. As you are aware, we have not defined the function println() we are just simply using it as it has been defined by the people that developed Processing, in other words we have not told the computer what to do when it comes across println() in our Hello World 1.0 program. This means that the main body defining how println() acts in our program is not defined within our program but exists independently of our program, probably somewhere else on your hard disk drive where you installed Processing. If we were to take another look at the Hello World 1.0 program, we can see the function println() is telling the machine, that the sketch is running on, to print whatever is inside the parenthesis. We call data we input to a function through parenthesis, parameters and some other higher level languages might refer to parameters as arguments. The parameters our println() function accepts in this case is the string of characters that spell out the words “Hello World”. Hello World Program 1.0 47
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