c# DateTime Picker - why is the 1st August 2020 earlier than the 26th July 2020?

[Dravinian]

This one has baffled me, and I can't work out why it is happening at all.

My code:

 

            string date1;
            string date2;


            date1 = datePicker1.Text;
            date2 = datePicker2.Text;
            
            int compareResult1 = date1.CompareTo(date2);

            if (compareResult1 < 0)

 

This works, if you put in the 26/07/2020 and then put in 25/07/2020, it will tell you that the second date is earlier than the first.

 

However, if I put the 27/07/2020 and then put in 01/08/2020 it will tell me that the second date is earlier than the first - which it is clearly not.

 

This is of course localised to my date format, so if you are using a different format, just assume that it is 07/27/2020 compared to 08/01/2020 and it is telling you that 08/01/2020 is earlier.

 

I did a massive amount of searching around DateTime, CompareTo, TryParse etc etc. and a lot of it is very old and refers to using a DatePicker.Value and DateTime...but there is no DatePicker.Value in WPF, and if you try many many many of the methods it comes back "cannot implicity convert to a string"

 

There must be a simple way to compare two dates from a DatePicker and say which one comes first?

 

After what I imagine is two hours of banging my head against Google I come seeking aid...

[Dravinian]

But bear in mind, it is now 3.30am so I am going to bed, any assistance will lauded greatly when I wake up.

Thanks.

[kirashi]

3 minutes ago, Dravinian said:

There must be a simple way to compare two dates from a DatePicker and say which one comes first?

 

Though I don't program in C#, the easiest way to implement a time/date picker is to use ONLY acceptable date format as per ISO8601 during the comparation stage. (Or you could calculate epoch time instead, since that's simply a fixed number that counts upward from its' starting date/time.)

[Chris Pratt]

Because you're not comparing dates; you're comparing strings, and the string "01/08/2020” comes before the string "27/07/2020”, because the char code for '0' is less than that of '2'.

 

Use `DateTime.TryParse` to convert the string to an actual `DateTime`, and then compare them.

[Dravinian]

9 minutes ago, Chris Pratt said:

Because you're not comparing dates; you're comparing strings, and the string "01/08/2020” comes before the string "27/07/2020”, because the char code for '0' is less than that of '2'.

 

Use `DateTime.TryParse` to convert the string to an actual `DateTime`, and then compare them.

dammit, I had gotten to the point of using int.TryParse(datePicker1.Text, out date1)

 

Did not, in all of my googling come across DateTime.TryParse.

 

Thank you, implemented and working pefectly.

 

I really do appreciate this actually, I couldn't turn my brain off trying to work out how to do this and I wasn't gonna fall asleep for long time without a fix...so very grateful thanks!

[Dravinian]

15 minutes ago, kirashi said:

Though I don't program in C#, the easiest way to implement a time/date picker is to use ONLY acceptable date format as per ISO8601 during the comparation stage. (Or you could calculate epoch time instead, since that's simply a fixed number that counts upward from its' starting date/time.)

The epoch time isn't a bad idea, and I did think about this and the Universal Time thing that counts up from 01/01/1970 or something (going from memory here they could be the same thing).

 

I just thought there had to be a better way.