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Index › Programming Questions & Help › Syntax Questions › what does void mean

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what does void mean? (Read 635 times)

fiorina Junior Member Offline Posts: 51	what does void mean? Jan 15^th, 2009, 6:08am I read in the reference it means no value is returned. But what does that mean? Why would I want to or would I not want to return a value? What's the point of void anyway? WHy can't it just be draw(), or setup()? For some reason the old answer "void doesn't return a value" doesn't mean much to my brain. blatant noob q i know... :S

theinhibitor

Re: what does void mean?
Reply #1 - Jan 15^th, 2009, 6:34am

Hey!
void is (in most langauges) a keyword to describe a function that does not return any value. for example;
Code:

void isPrime(int i) //does not return a value when called
boolean isPrime(int i) //returns a boolean (true or false) value

Your would call each function respectively:
Code:

isPrime(5); //no value is returned
boolean t = isPrime(5); //t = true;

BTW special functions CANNOT be changed (unless they are overwritten in a class). For instance, you cannot make a function called int draw() as it will conflict with void draw() which is already defined.
If i were you, I would look at a beginning tutorial of java/C. You dont even need to code anything, just follow what the author says.
Goodluck

"AAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH"&&-Goku

PhiLho

Re: what does void mean?
Reply #2 - Jan 15^th, 2009, 11:31am

Good explanation above, I will just add some info.

Note that class constructors have no return type!
So the void brings some information: 1) This function is not a constructor, 2) It states explicitely the nature of the function.

Unlike some languages (JavaScript, Lua, JavaFX...), there is no "function" keyword marking functions as such. So the syntax of a function is:
<return type> [<optional visibility modifiers>] <function name>([<optional list of parameters>]) { <body of function> }

The problem is that code like: f() { /* Some code */ } would be seen as: call of f, start a block (delimiting a scope), code, end the block. You can start a block anywhere, it doesn't have to follow a conditional or such.
So it would no longer be a function definition but a function call!

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