Bid and Ask appears to return current, even when BackTesting...

I wrote the following code in an indicator:


int start()
{
if ( firstRun ) {
WindowScreenShot("WTFTEST.GIF",1024,768);
int handle = FileOpen("WTFTEST.TXT",FILE_WRITE);
FileWrite(handle,Bid + ","+Ask);
FileClose(handle);

firstRun = false;
}
return(0);
}

When I ran it while backtesting, the screen shot showed the chart with the backtest time and prices, but the text file contained Bid and Ask prices from current server feeds (i.e. present values, not values relative to the backtest timeframe.)

What is going on, here?

(a) is there another API I should be using?
(b) does that infer that I should not use "Bid" and "Ask" APIs in my EAs and indicators?

By definition, Ask is the latest known seller's price (ask price) for the current symbol.

In indicator, Ask and Bid will always return latest price. As CodeMeister said above, there is no Ask[] and Bid[]. To get latest price shown on chart by indicator, use Close[0]. This is Bid value.

If you want Ask and Bid value relative to strategy tester chart, you should access them in EA directly. Simply put your statements that contain in indicator's start() routine to start() routine of EA will give the expected result.

And because MT4 don't record spread in history file, Ask-Bid in history price always equal to the latest spread you get from server

Sangmane: Thank you. It sounds like the answer to my question (a) is "yeah, use Close[0] in an indicator," and (b) is, "No, don't use Bid() and Ask() in Indicators if you want to be able to backtest them." It sounds like you've also told me that Bid() and Ask() will work as expected (by me :-) ) in an EA while backtesting. Have I read you correctly?

CodeMeister: I read the page at http://docs.mql4.com/predefined/variables/bid a long time ago - I was looking for a little more. Perhaps the following would have been more helpful: "By definition, Ask is the latest known seller's price (ask price) for the current symbol. Unfortunately, in an Indicator, this information is provided in context of current time, not backtest time." (It's still an open question - see above, whether the information is provided in context of a running backtest when executed in an EA.)

In any case, thanks to both of you. The help is appreciated.

Umm, there is misunderstanding.

1. There is no Bid() and Ask(). There's only Bid and Ask. I never told about Bid() and Ask().
2. There is no Bid[] and Ask[]. The way array is wrote is append "[]" after vars name. What I meant was that MT4 dont provide array of Bid and Ask, like Ask[i], Bid[i]. Accessing Bid and Ask from inside indicator will give the latest value of Bid and Ask, regardless the chart where the indicator attached to. If your MT4 is not connected to server, than you'll get the latest Bid/Ask stored on history file.
3. Accessing Bid and Ask from inside EA during backtesting will give the latest price shown on backtester's chart

Sample EA:

hope this help

Sangmane: No misunderstanding. Just a syntactical error on my part. I should have used Bid & Ask in my narrative, as I did in my code sample.

It's a variable, not a function...

So tell me - the one thing I think you said, but have not seen you confirm, is that Bid and Ask, when used in an EA, provide (an estimated) Bid and Ask value in context of the currently-running backtest. Is this true?

If so, then I think I presume correctly that the estimation has to do with using whatever the truly current (i.e. now, not in the BackTest) spread is, along with the most recent recorded transaction, to synthesize a bid and ask - they are not the truly historical Bid and Ask values...

Thank you very much for your clarification.

Regards,

S.

Squanto,

Firstly, please note that my knowledge in MQL is most come from doing backtesting (trial and error things, you know that). By the lack of a full/detail MQL reference, there's nothing I can do except doing experiment and read other's experiences as well.

Here are what knowledge I've got so far:
1. MT4 record each tick value it got from server, in its history file. Every tick contains Bid and Ask value. What type of value being recorded? IMO, is Bid value. So, no need to estimate Bid value. Will EA provide Bid value in context of currently running backtest - yes. Will indicator do the same? No. How to get Bid value from inside indicator in context of currently running backtest? Use Close[0], 'cos Close[0] = Bid value.

2. Ask = Bid + spread. By having truely Bid value, and the last known spread, MT4 only need to synthesize Ask.

Try this short EA
Regards,

S.

Sangmane, thank you very much for your help. As I said above, it is greatly appreciated.

Regards,

Squanto.

So, there's no way to get the real spread (variable) from history in backtesting even if the csv file converted to fxt file has the real ask and bid prices on it ? Thanks.