HoursBetween

[Henry Olive 5]

Good Day,
Delphi 10.3

 

procedure TForm2.Button1Click(Sender: TObject);
  var
  ST,ET : TDateTime;
  Diff : Double;
begin
  ST := StrToDateTime (Edit1.Text); // Text = 08:00
  ET := StrToDateTime (Edit2.Text); // Text = 11:30

  Diff := HoursBetween(ST,ET);
  Edit3.Text := FloatToStr(Diff);

The result of above proc is 3

i was expecting  3,5

Thank You


 

 

end;

[toms 29]

Maybe use StrToTime()

[Stano 143]

Why do you use TEdit and not TTimePicker etc.? They are intended for this purpose. It's a big mistake for me!

[Henry Olive 5]

Thank you so much Tom, Stano

Stano, i know TDateTimePicker is good solution

but i want to learn to get time difference between 2 strings

[PeterBelow 238]

17 minutes ago, Henry Olive said:

Good Day,
Delphi 10.3

 

procedure TForm2.Button1Click(Sender: TObject);
  var
  ST,ET : TDateTime;
  Diff : Double;
begin
  ST := StrToDateTime (Edit1.Text); // Text = 08:00
  ET := StrToDateTime (Edit2.Text); // Text = 11:30

  Diff := HoursBetween(ST,ET);
  Edit3.Text := FloatToStr(Diff);

The result of above proc is 3

i was expecting  3,5

 

That's just like HoursBetween works, the return value is an integer, so the difference is rounded to the next full hour. Use MinutesBetween and divide the result by 60 if you want the difference to be in fractional hours.

[Uwe Raabe 2057]

You can achieve the desired result with TTimeSpan:

  diff := TTimeSpan.Subtract(ET, ST).TotalHours;

 

[Henry Olive 5]

Thank you  SO MUCH  Peter, Uwe

[Henry Olive 5]

Good Day,

 

ST := Start Time

ET := End Time

What if 

ST:='17:30' and ET :='00:00'  (The Difference should be 6,50 but i get 17,50)

 

If i change '00:00' to '12:00' this time the Difference is 5,50 not 6:50

if i change '00:00' to '24:00' then this time 24:00 is not valid datetime error msg.
 

Thank You

 

Edited September 26, 2022 by Henry Olive

[PeterBelow 238]

8 minutes ago, Henry Olive said:

Good Day,

 

ST := Start Time

ET := End Time

What if 

ST:='17:30' and ET :='00:00'  (The Difference should be 6,50 but i get 17,50)

 

If i change '00:00' to '12:00' this time the Difference is 5,50 not 6:50
 

 

 

With the 24 hour clock 00:00 is interpreted as midnight starting the current day and 24:00 as midnight ending the day.

[Henry Olive 5]

Thank You Peter

I edited my last post 6 minutes ago if you can check

i tried also 24:00

[Henry Olive 5]

Here below my codes

 

procedure TForm2.Button1Click(Sender: TObject);
  var
  ST,ET : TDateTime;
  Diff : Double;
begin
  if (ComboBox1.Text='') or (ComboBox2.Text='') then Exit;

  ST := StrToDateTime (ComboBox1.Text);  '17:30'
  ET := StrToDateTime (ComboBox2.Text);   '24:00'
  Diff := MinutesBetween(ET,ST) / 60;

  Edit1.Text := FloatToStr(Diff);
end;

[David Heffernan 2345]

The problem is that your code is based on an assumption that the end time is after the start time, but 00:00 is the beginning of the day and so can never be used as an end time. Hard to advise you what to do because we don't know your goals, where your data is coming from, how you want to handle day boundaries etc. 

[Henry Olive 5]

Thank You so much David

User enters the StartTime & EndTime by hand ( by choosing from the combox Items)

Each ComboBoxes has  Items

17:30,

18:00

19:00

...

24:00

 

Between 17:30 to 24:00

 

 

Edited September 26, 2022 by Henry Olive

[zed 14]

Start of the next day is the end of the current day, so you can write:

var
  a, b: TDateTime;
begin
  a := StrToDateTime('17:30');
  b := StrToDateTime('00:00') + 1; // 24:00

  WriteLn(MinutesBetween(b, a)); // 390

 

[Uwe Raabe 2057]

9 minutes ago, zed said:

b := StrToDateTime('00:00') + 1; // 24:00

Well, that can obviously be simplified to b := 1;

[David Heffernan 2345]

18 minutes ago, Henry Olive said:

Thank You so much David

User enters the StartTime & EndTime by hand ( by choosing from the combox Items)

Each ComboBoxes has  Items

17:30,

18:00

19:00

...

24:00

 

Between 17:30 to 24:00

 

 

They can only choose from these 14 items?  Why do you need any conversion?  Isn't it just (EndIndex - StartIndex) / 2?

[Henry Olive 5]

Thank you so much  Z, Uwe, David

David, Yes They can only choose from these 14 items

I'm sure you you suggested me a short & clever way but

what you mean by (EndIndex - StartIndex) / 2 ?

 

[mvanrijnen 123]

1 hour ago, David Heffernan said:

They can only choose from these 14 items?  Why do you need any conversion?  Isn't it just (EndIndex - StartIndex) / 2?

i use about the same method in our planner (with a timeoffset and a flexible interval (as setting for the user)).

 

function TframeEditFromTill.ComboToTime: TTime;
begin
  Result := TimeOf(IncMinute(0, TimeOffSet + (cmbTimeTo.ItemIndex*EditTimeInterval)));
end;

* TimeOffSet is a integer property, just to have the possibility to force a mininum time 

* EditTimeInterval is a integer property, the interval in minutes e.g. 5, 15, 30

 

Edited September 26, 2022 by mvanrijnen

[Lars Fosdal 1792]

@Henry Olive - (EndIndex - StartIndex) / 2
17:30 - 17:30 = (0 - 0) / 2 = 0
17:30 - 18:00 = (1 - 0) / 2 = 0.5
18:00 - 18:30 = (2 - 1) / 2 = 0.5
...
17:30 - 00:00 = (13 - 0) / 2 = 6.5
23:30 - 00:00 = (13 - 12) / 2 = 0.5

[Pat Foley 51]

So with (48 - 1) half hour INTERVALS in each day using Combos do this 



         comboBoxStart.items.add(00:00)

        ...

        comboBoxStart.items.add(12:00)

        ...

       comboxBoxstart.items.add(23:30)

      comboxBoxStart.items.add('Tomorrow');


       

     or 

      comboboxStart.items.add('yesterday')

      comboBoxStart.items.add(00:30)

        ...

       comboBoxStart.items.add(12:00)

        ...

       comboxBoxstart.items.add(24:00)



Do same for comboBoxStop 

       ...
        

      StartHour :=  (combobox.selectedIndex / (24 * 2)) * 1{full day fraction that is 48/48}  

      ...

 

Edited September 26, 2022 by Pat Foley
combo Box Fix up touched.

[Henry Olive 5]

Thank You SO MUCH  Mvanricnen, Lars, Pat

[limelect 48]

Rx librery in it use RxDateUtil.pas