I am, obviously unsuccessfully, trying to paste datetime into string:
datetime dt_EAExpires=D'2016.12.31 23:59';
extern string EA_expires_txt="--- EA expires on: "+TimeToString(dt_EAExpires,TIME_DATE|TIME_MINUTES)+" ---"; /*2016.12.31 23:59 ---";*/ // --- EXPIRATION DATE ---
This raises an error: '+' - constant expected OmChi EA.mq4 76 101
Adding 'const' before datetime does not solve the issue.
S love nia
You cannot use variable expressions (such as calls to functions) when setting the initial value of an "extern" or "input" variable/parameter. They are presented to the user before execution begins, so they have to be of a constant nature.
You can however, change the value of "extern" parameters within the EA execution, such as in the OnInit() or OnTick(), but you cannot change "input" variables.