function explanation

[chic0]

Hello, I just started learning AS a day or 2 ago :glasses:
Now, I don't really understand how to use functions,
I read the function page on kirupa.com, but I saw other (random) files where the functions included a lot of information between the brackets..
like:
test = function(a, b, c, d, e, ...){
}

Could anybody help me understand when/why to use all that data?

I tried google, but than didn't help :blush:

Thanks,

[lostinbeta]

Those are called arguments, you can use them to dynamically change the value of a variable/item within the function... for example...

function doubleNum(num) {
return num*2;
}
trace(doubleNum(3));//returns 6 in the output window

Of course that function is utterly useless, but it's an example.

You can add as many arguments as you want, as long as they are seperated by a ','.

[maximum_flash]

also, it is important to note that arguments have to be passed to the function in the same order as they are required.

for example:



function quotient (a, b){
trace (a/b)
}


when you call it, you must give the values in the same order. if you do not give a value, the value is given the default of "undefined"

so, when calling it:



quotient (4, 2) // would output 2


if these parameters had not been passed properly, you would have had some pretty adverse results.

basically the same thing lostinbeta said, just a little more you should know about arguments in functions. good luck!

*edit* // can't spell

[chic0]

Ok, so:
Parameters are handy because u can specify different values each time you use the function.
But u can also let the function work without these parameters? (static values)

Greetz

[lostinbeta]

Correct.

Arguments are not required when writing a function. However, if you do define an argument and use that argument within the function, you need to be sure to add it within the call of the function otherwise it will be passed to the function as null/undefined.

[tofuisonmyside]

my 2 cents.

a function is a set of actions to make something.
for example, you want to position a movie clip on stage

you can create a function for this task.
//supposing you have a movieclip named myMC on stage

function position_MC(){
myMC._x = 50
myMC._y = 120
}
position_MC()//call the function

you can see this is correct but it can be used with params

function position_MC(x,y){
myMC._x = x
myMC._y = y
}
position_MC(50,120)//call the function

better but you can do more things, for example, use this function for all your movieclips on stage

function position_MC(mc,x,y){
mc._x = x
mc._y = y
}
position_MC(myMC,50,100)//call the function

Hope this helps

[lostinbeta]

better but you can do more things, for example, use this function for all your movieclips on stage

function position_MC(mc,x,y){
mc._x = x
mc._y = y
}
position_MC(myMC,50,100)//call the function

Hope this helps

And to elaborate on that note, after you have a full understanding on how functions work and how/when to use them. When it comes to things like the above where you need to target objects and/or movieclips you can get into prototypes...

MovieClip.prototype.position_MC(x, y){
this._x = x;
this._y = y;
}
//useage
myClipsInstanceName.position_MC(50, 100);

But that is for the future after you have a better understanding of basic functions, targeting, etc.