[amibroker] Re: Difference between 0 and Null for variables?

["tuzo_wilson" <j.tuzo.wilson@xxxxxxxxx>]

--- In amibroker@xxxxxxxxxxxxxxx, "ozzyapeman" <zoopfree@xxx> wrote:

> What is the difference, if any, between 0 and Null when assigning
> non-boolean variables? When should we use Null instead of plain old 0?

Some good posts on this so I won't repeat what has been said.  
In your example, variables that will be assigned to later (e.g.
valueAtBuy) are initialized to Null.  Variables that are going to be
incremented (e.g. longContractCount) are initialized to 0.

That makes sense from a common sense point of view.  What is the
valueAtBuy before there is a buy?  Who knows -- there is no value yet.
 How many long contracts do you have before you enter into any long
contracts?  This is known -- you have zero contracts.


Tuzo

> For example, all of the six variables below are real numbers, yet some
> are initially set to Null and others to 0.
> 
> I copied this snippet from an example AFL that works properly:
> 
> 
> // Set up variables for our entry values, as our stops will test
> // against the initial entry prices
> 
> valueAtBuy = valueAtShort = Null;
> profitLevel = profitLevel2 = Null;
> 
> 
> // Number of open contracts
> 
> longContractCount  = 0;
> shortContractCount = 0;
> 
> for (i = start; i < BarCount; i++)
> {
>



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