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How to dynamically define an array

  • #1
  • First Post: Edited 3:35pm Jan 22, 2011 2:46pm | Edited 3:35pm
Hi, everyone,

Could anyone tell me how I should correct my following code so that it works? Many thanks!

Inserted Code
extern int NumOfTestBar=100;

int start()
{
   double EMA13[NumOfTestBar];
   ....
}
  • #2
  • Jan 22, 2011 4:23pm Jan 22, 2011 4:23pm
Arrays have to be declared with fixed sizes as in:

Inserted Code
Double EMA13[9]
They can be dynamically re-sized by using ArrayResize() at some point later in the code. In your case, it would look something like:

Inserted Code
ArrayResize(EMA13, NumOfTestBar);
  • #3
  • Jan 22, 2011 4:45pm Jan 22, 2011 4:45pm
Many thanks! Should the resized array smaller than the declared size? Or it can be resized to a larger array?

Many thanks!


Quoting CodeMeister
Arrays have to be declared with fixed sizes as in:

Inserted Code
Double EMA13[9]
They can be dynamically re-sized by using ArrayResize() at some point later in the code. In your case, it would look something like:

Inserted Code
ArrayResize(EMA13, NumOfTestBar);
  • #4
  • Jan 22, 2011 5:16pm Jan 22, 2011 5:16pm
Quoting dogberry
Many thanks! Should the resized array smaller than the declared size? Or it can be resized to a larger array?

Many thanks!
I don't have much experience with it other than seeing it in others code, but I think I remember reading it could be used for both purposes. That makes sense if you need to vary the size according to the amount of data to analyze.
  • #5
  • Jan 22, 2011 9:15pm Jan 22, 2011 9:15pm
Just leave the size blank :-

Inserted Code
Double EMA13[]
  • #6
  • Last Post: Jan 22, 2011 10:56pm Jan 22, 2011 10:56pm
I wrote a little something couple of years back that may be helpful for you in learning Arrays in MQL.

Article: Effective usage of Arrays in MQL

Hope it helps.

regards,
Zen
Programming for a better future.
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