CODEWITHSUNDEEP
constantsdefault-valueexternmql4
Andrea Caronello
Andrea Caronello

Reputation: 217

MQL4 - How to set a "today"-datetime to an extern variable in MQL4 script?

I have an MQL4 script ( a script that runs on MetaTrader4 Terminal platform ) and I need to define an extern variable, named extractionDate of type datetime, so that the user can change its input value before the script starts.

I tried the conventional way to define the variable before the standard script's function start(), but it doesn't work. When I compile I, get the error message

['TimeLocal' - constant expected]

that means MQL4 wants a constant value for the variable. But this isn't my goal. I would like to show as default value the "Today" date, when the script starts and not a fixed predefined date value.

Is it possible to do this or not?

extern datetime extractionDate = TimeLocal();
int start()
{
   ......
   return(0);
}

Upvotes: 2

Views: 1000

Answers (1)

user3666197
user3666197

Reputation: 1

No, compiler does not allow this directly

Compiler does not allow a way to assign a default value, that is not constant. It has to know the value, so an attempt to setup / assign an unknown / variable-value as a default one, will yield compilation error.

Yet, how to solve this?

My approach would be to give user instructions and a choice to setup any datetime, or setup a value of -1, which would be translated inside the OnInit() event handler code-block:

 void   OnInit(){
        ...
        if (  extractionData == -1 ) extractionDate = TimeLocal();
        ...
        }

Upvotes: 3

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