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Author: Andy Armistead (with a little help from FlashGuru)

### Our first Custom Function

Now, we dont really expect Flash to go shopping for us (though in the wonderful world of online shopping even this might be possible). Lets look at a real example of a useful function that we could regularly use in Flash.

We are going to write a function that will work out percentages for us. So, the way we usually say this is something like:

10 out of twenty is fifty percent.

I havent done maths in many a year, but I do remember that we work out a percentage by doing:

Number divided by the total possible. Then times it by 100 and thats your percentage
So this translates to:
```(number/total)*100 = percentage
```
(because in flash the / means divide by and the * means multiply by).

That is the task that we want to do, so in the same way as we did for shopping we would define the tasks as:

```function percent() {
percentage = (number/total)*100;
}
```
Weve given the function the name percent and told it what tasks it needs to do. Easy!

#### Work out the parameters

In order to do the tasks in the percent() function, it needs to know what value number has and what value total has, then it can do the rest. So we tell it to expect these values by specifying them as parameters:

```function percent (number,total) {
percentage = (number/total)*100;
}
```
Notice, that because we need to give two different parameters, we can just put them inside the round brackets separated by a comma. Pretty straightforward eh? Because we are defining the function, we can put as many and as few parameters as we like. Thats one of the beauties of writing custom functions you get to decide everything.

#### Getting the return

The point of doing this function is that we want to get the percentage back from it. Otherwise, thered be little point in doing it. So we need to return the percentage.

```function percent(number,total) {
percentage = (number/total)*100;

return percentage;
}
```
Nothing could be easier.

#### Using the function

Remember from our shopping example, we needed something to put the food in, so we used a variable cupboard that would hold the food that the function returned. Well here, were returning the percentage so when we call the function we need to give it somewhere to put the returned value. Were going to use a variable called pcent. You could call the variable anything you like, the function wont be picky; itll put the returned value into whatever you tell it to.

So for our example, when we call the function we might do something like:

```pcent = percent(10,20);
```
this tells flash to do the tasks inside the function called percent(). It tells it that the value of number is 10 and that the value of total is twenty. Flash then goes off and works it all out for you and puts the result into the variable called pcent. So in this case pcent will be set to 50.

One thing to keep in mind here: The order of the parameters is important. If I do:

```pcent = percent(20,10);
```
then Flash will do:
```percentage = (20/10)*100;
return percentage;
```
which would give us a completely different result. In this case pcent would equal 200.
When you use a function, it is important that you give it the values it needs in the right order, otherwise the results you get will not be what you expected!

 » Level Basic Added: 2001-05-16 Rating: 8 Votes: 185 1 2 3 4 5 6 7 8 9 10 (10 being the highest) » Author No details available. » Download Download the files used in this tutorial. Download (0 kb) » Forums More help? Search our boards for quick answers!

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