Get firstDate previous month & lastDate previous month?

I want get firstDate previous month & lastDate previous month ?

Example Now 12/04/2565

I want to FirstDate as String = 25650301 (Format yyyyDDMM)
and LastDate as string = 25650331 (Format yyyyDDMM)

Please guide me about it

use my sequence for reference
test11.xaml (8.6 KB)

you declare DateTime nowDate and set it to your date
then calculate first date of current month, and from that the last and first date of prev month

1. nowDate = DateTime.ParseExact("12/04/2565", "dd/MM/yyyy",nothing)
2. dFirstDayOfThisMonth = nowDate.AddDays(-(DateTime.Today.Day-1))
3. dLastDayOfLastMonth = dFirstDayOfThisMonth.AddDays (-1)
4. dFirstDayOfLastMonth = dFirstDayOfThisMonth.AddMonths(-1)


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Hi @fairymemay ,

Here is an alternate solution →

First date of previous month:


Last date of previous month:


FirstndLastDatePrevMonth.xaml (5.3 KB)

Kind Regards,
Ashwin A.K

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If I don’t fix date = 12/04/2565 —> check auto ?

DateTime.ParseExact("12/04/2565", "dd/MM/yyyy",nothing)

How to edit it?

if you want auto date do this

nowDate = Now()


I guess 2565 is Buddhist era, right? If so, the following expression will work and can also handle leap year correctly.

strDate = "12/04/2565"
dateVar = DateTime.ParseExact(System.Text.RegularExpressions.Regex.Replace(strDate,"\d{4}$",Function(m) (Int32.Parse(m.Value)-543).ToString()),"dd/MM/yyyy",System.Globalization.CultureInfo.InvariantCulture)


System.Text.RegularExpressions.Regex.Replace(New DateTime(dateVar.Year,dateVar.Month,1).AddMonths(-1).ToString("yyyyMMdd"),"^\d{4}",Function(m) (Int32.Parse(m.Value)+543).ToString())

System.Text.RegularExpressions.Regex.Replace(New DateTime(dateVar.Year,dateVar.Month,1).AddDays(-1).ToString("yyyyMMdd"),"^\d{4}",Function(m) (Int32.Parse(m.Value)+543).ToString())

If you need to use today’s date, please try dateVar = Now


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