Inverse function of FormatDateTime

Question

I am looking for a function to reverse any string (YYYYMDD,YY/MM/DD,YYMMDD,...) created by the function FormatDateTime to

Answer 1

Note: Unfortunately, as pointed out by Martien in this answer's comments, this solution will not work for cases where the date includes no date separator. However, I'm going to leave the answer up for anyone that may find it useful regardless.

I liked Tuncay's answer but there were a couple of problems with it. I'd have left a comment but I don't have enough reputation points.

So, here's the corrected version of Tuncay's answer (amending "TFormatSetting" missing an "s" and specified the format settings date separator):

function AnyStringToDate(fmt, dt: String) : TDateTime;
var
  fs : TFormatSettings;
Begin
  fs := TFormatSettings.Create;
  fs.DateSeparator := '-';
  fs.ShortDateFormat := fmt;

  result := StrToDateDef(dt, 0, fs);
End;

Identical to Tuncay's answer, AnyStringToDate can be used as follows:

mydate := AnyStringToDate('YYYY-MM-DD', '2015-01-20');