Delphi: DateTimeToStr output with zero time (midnight) - delphi

Question

I have found a similar question here, but it is unrelated to what I am trying to do. I have done a lot of research on the Internet and I have determined that Delphi is working as designed or intended, where it omits the time if the time is zero. I have an application which displays the date & time in a listview, and when the time is midnight, it doesn't show 00:00:00, and therefore making the results look uneven and out of place.
The way I've gotten around this which is still locale independant is to add a microsecond to the time, see sample code:
program Test11;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils, Winapi.Windows;
begin
try
Writeln(DateTimeToStr(44167, TFormatSettings.Create(GetThreadLocale)));
Writeln(DateTimeToStr(44167.00000001, TFormatSettings.Create(GetThreadLocale)));
Readln;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
end.
And subsequent output:
02/12/2020
02/12/2020 00:00:00
The question is - is there a better, more programatically correct way to do achieve this?
Running Delphi XE6

Answer 1

You can use FormatDateTime function for more control over date time formatting.
FormatDateTime('ddddd tt', 44167, TFormatSettings.Create);
Note: There is no need to call TFormatSettings.Create(GetThreadLocale) with locale parameter because plain TFormattSettings.Create call will internally use GetThreadLocale on Windows platform.

Answer 2

This is "normal" behavior of VCL. Look at the related code from System.SysUtils (it is from Seattle, but I think it hasn't much changes since XE6).
function DateTimeToStr(const DateTime: TDateTime;
const AFormatSettings: TFormatSettings): string;
begin
DateTimeToString(Result, '', DateTime, AFormatSettings);
end;
procedure DateTimeToString(var Result: string; const Format: string;
DateTime: TDateTime; const AFormatSettings: TFormatSettings);
begin
...
if Format <> '' then AppendFormat(Pointer(Format)) else AppendFormat('C');
...
//This is another related part of DateTimeToString.
case Token of
'C':
begin
GetCount;
AppendFormat(Pointer(AFormatSettings.ShortDateFormat));
GetTime;
if (Hour <> 0) or (Min <> 0) or (Sec <> 0) or (MSec <> 0) then
begin
AppendChars(' ', 1);
AppendFormat(Pointer(AFormatSettings.LongTimeFormat));
end;
end;
If time part of datetime value equals to zero, then only date will be in result string.
If you want always show datetime in single format, better use FormatDateTime as suggested by other answers.