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Simple Question about For Loops

  • #1
  • First Post: Sep 30, 2010 3:38am Sep 30, 2010 3:38am
for (i = 0; i < 5; i ++)
{
bar = bar + 1;
}

Does the for loop start adding 1 to i first, or does it start of at 0 and then add 1 after the completion of the first loop?

Does the for loop stop executing at i = 5, or i = 4 ?
  • #2
  • Sep 30, 2010 5:35am Sep 30, 2010 5:35am
hey mindreality..... asumming you have int i; also in the code, it does your second choice.....

it start of at 0 and then add 1 after the completion of the first loop....

and it would keep looping as long as i was < 5 which would be 4.....

a total of 5 loops...... 0,1,2,3,4 ......h
to trade and code, keep both simple... no call to impress....h
  • #3
  • Sep 30, 2010 10:03am Sep 30, 2010 10:03am
So let's say I want to check if the low of the 4 previous bars are above the price x, I do the following loop right?

for (int i = 1, i < 4, i ++)
{
if Low[i] > x;
barabovex = true;
}


And not

for (int i = 0, i < 5, i ++)
{
if Low[i] > x;
barabovex = true;
}


Which one of the above two is correct? i should be set to 1 and not < 4 right? Which means it would start checking from one bar back until the forth bar back right?
  • #4
  • Sep 30, 2010 10:15am Sep 30, 2010 10:15am
What I am trying to do is to compare the current time to a certain time back in the past and see if the low has crossed a certain level.

For example, the time is currently 8:45 and I am using the 30 min chart which means the current bar is the 8:30 bar. I want to check the Low of the current and the previous bars until the 5:30 bar. That is about 6 bars in total.

datetime StartBarTime = StrToTime("5:30");

for (timecount = 0; timecount < ((TimeCurrent() - StartBarTime)/60/30); timecount ++)
{
if Low[i] > x;
barabovex = true;
}


Is it correct?
  • #5
  • Sep 30, 2010 10:44am Sep 30, 2010 10:44am
might be simplier to use ilowest.....h


double low = Low[iLowest(NULL,0,MODE_LOW,5,0)];

if(low > x)
{
baroverx = true;
}
to trade and code, keep both simple... no call to impress....h
  • #6
  • Sep 30, 2010 11:00am Sep 30, 2010 11:00am
The thing is, the number of bars I want to count back is dynamic.

Lets say I want to count from the current bar all the way back to the 5:30 bar, the current bar could be 8:30, 9:00, 9:30... etc.

So I can't use a static number of bars as the mode such as when using iLowest.

I need to implement a For Loop to count backwards from the current bar up to the 8:30 bar in the past.

What is the way to do it?
  • #7
  • Sep 30, 2010 11:25am Sep 30, 2010 11:25am
Quoting mindreality
What is the way to do it?
Maybe something like this:

Inserted Code
 
   double x = 1.30000;
   bool baroverx = false;
   datetime backtime = StrToTime( "05:30" );
   int backshift = iBarShift( Symbol(), Period(), backtime );
   double low = Low[iLowest(NULL,0,MODE_LOW,backshift+1)];
   if(low > x)
   {
      baroverx = true;
   }
  • #8
  • Sep 30, 2010 12:02pm Sep 30, 2010 12:02pm
Quoting zznbrm
Maybe something like this:

Inserted Code
 
   double x = 1.30000;
   bool baroverx = false;
   datetime backtime = StrToTime( "05:30" );
   int backshift = iBarShift( Symbol(), Period(), backtime );
   double low = Low[iLowest(NULL,0,MODE_LOW,backshift+1)];
   if(low > x)
   {
      baroverx = true;
   }

Thanks! I think this is exactly what would do it.
  • #9
  • Sep 30, 2010 12:37pm Sep 30, 2010 12:37pm
Quoting zznbrm
Maybe something like this:

Inserted Code
 
   double x = 1.30000;
   bool baroverx = false;
   datetime backtime = StrToTime( "05:30" );
   int backshift = iBarShift( Symbol(), Period(), backtime );
   double low = Low[iLowest(NULL,0,MODE_LOW,backshift+1)];
   if(low > x)
   {
      baroverx = true;
   }

Btw, is there a missing variable?

int iLowest( string symbol, int timeframe, int type, int count=WHOLE_ARRAY, int start=0)

Which means iLowest(NULL,0,MODE_LOW,backshift+1,??????)

Is there a need to put in the Shift parameter which shows the bar, relative to the current bar, that the data should be taken from?

Also, why is it backshift+1 instead of just backshift?
  • #10
  • Sep 30, 2010 1:26pm Sep 30, 2010 1:26pm
Quoting mindreality
Btw, is there a missing variable?

int iLowest( string symbol, int timeframe, int type, int count=WHOLE_ARRAY, int start=0)

Which means iLowest(NULL,0,MODE_LOW,backshift+1,??????)
Last parameter defaults to 0.

Quote
Is there a need to put in the Shift parameter which shows the bar, relative to the current bar, that the data should be taken from?

From this statement:

"What I am trying to do is to compare the current time to a certain time back in the past and see if the low has crossed a certain level."

I took it to mean you only interested in the current time (ie, bar zero).

Yes, you would need to use the Shift parameter for something other than the current time (bar zero).

Quote
Also, why is it backshift+1 instead of just backshift?

Let's say backshift is 10 and start bar is 0. That is 11 bars, not 10.
  • #11
  • Sep 30, 2010 1:37pm Sep 30, 2010 1:37pm
Quoting zznbrm
Last parameter defaults to 0.



From this statement:

"What I am trying to do is to compare the current time to a certain time back in the past and see if the low has crossed a certain level."

I took it to mean you only interested in the current time (ie, bar zero).

Yes, you would need to use the Shift parameter for something other than the current time (bar zero).



Let's say backshift is 10 and start bar is 0. That is 11 bars, not 10.
So let's say I want to count backwards to the 05:30 bar and check for all the lows. The current bar is 8:30. So backtime is "05:30"

So, int backshift = iBarShift( Symbol(), Period(), backtime );

backshift would equal 4 right?

And then, double low = Low[iLowest(NULL,0,MODE_LOW,backshift+1)];

I would calculate from Low[0] all the way to Low[4] is it?

Low[0], Low[1], Low[2], Low[3], Low[4] which is 5 bars, which is backshift+1

So that means I would be checking for all the lows of the 5:30, 6:00, 7:30, 8:00 and 8:30 bars am I right?
  • #12
  • Oct 1, 2010 12:53am Oct 1, 2010 12:53am
If anyone else who sees this message can confirm with me first, that would be great as well =)
  • #13
  • Oct 1, 2010 8:18am Oct 1, 2010 8:18am
hey mindreality..... might be easier just to code it and see.... or use the print function.....

a picture with the exact info marked in place really helps us understand your full goals...... otherwise we only have what someone writes to go on and you would not believe how difficult that can be......

ea below should help make it clear......h
Attached Image (click to enlarge)
Click to Enlarge Name: reaility2.gif Size: 41 KB
Attached File(s)
File Type: mq4 delete reailty.mq4   2 KB | 366 downloads
to trade and code, keep both simple... no call to impress....h
  • #14
  • Oct 1, 2010 12:42pm Oct 1, 2010 12:42pm
Hi,

From the chart it looks if I do not wish to measure the low of the 5:30 bar, then I only use backtime instead of backtime+1 right?

How did you get the information displayed on the chart? Where do I find the print function if that is what you used?
  • #15
  • Last Post: Oct 1, 2010 12:44pm Oct 1, 2010 12:44pm
Quoting mindreality
Hi,

From the chart it looks if I do not wish to measure the low of the 5:30 bar, then I only use backtime instead of backtime+1 right?

How did you get the information displayed on the chart? Where do I find the print function if that is what you used?
Correction, I mean backshift+1, not backtime+1
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