Is there an 'IsDate' function in b4a?

GaryOCO · Jul 14, 2013

IF I get a user to type in a date or submit a date string to a sub routine, I need to know, or be able to check, that a correct date string has been entered.

In VB I can check if a string is a legitimate date by calling the 'IsDate' function...

If IsDate(DateString) Then 'Check that DateString is a legitimate date string
'Do something
Else
'Do something else
End IF

I can also format a date string using the 'Format' function...

DateString = Format(Now,"dd/MMM/yyyy")

Can these results be achieved easily in B4A?

Erel · Jul 14, 2013

Questions should be posted in the questions forum.

B4X:

Sub IsDate(DateString As String) As Boolean
 Try
  DateTime.DateParse(...)
 Return True
 Catch
  Return False
 End Try
End Sub

mc73 · Jul 14, 2013

Irrelevant a bit, but in such occasions, I find it appropriate to use the dateDialog.

sirjo66 · Jul 14, 2013

GaryOCO said:
I can also format a date string using the 'Format' function...

DateString = Format(Now,"dd/MMM/yyyy")

Can these results be achieved easily in B4A?

Yes, for example:

B4X:

Dim now As Long
now = DateTime.now
DateTime.DateFormat="dd/MM/yyyy"
DateString = DateTime.Date(now)

Sergio

barx · Jul 14, 2013

The solution I have been using is very similar to Erels. The sub I came up with was.

B4X:

Public Sub IsDate (date As String) As Boolean
   Dim dateticks As Long
   
   date = date.Replace(".", "/")
   date = date.Replace("-", "/")
   date = date.Replace("\", "/")
   
      Try
         dateticks = DateTime.DateParse(date)
         If DateTime.GetYear(dateticks) > 1901 Then
            Return True
         Else
            Return False
         End If
      Catch
         Return False
      End Try
End Sub

The Replace statements allow other separators to be used '.', '-' or '\'. A but more tolerant to user input.

The Year Check if statement can be removed, that is just in as this particular app needed it

Seems to work fine for me.

Theera · Jul 15, 2013

Hi barx,
I think yours isn't always corrected,if it's "2013/02/28" or "28/02/2013"

B4X:

Public Sub IsDate (date As String) As Boolean
   Dim dateticks As Long
      Try
                     dateticks=Format(DateTime.DateParse(date),"dd/MMM/yyyy")
             If DateTime.GetYear(dateticks) > 1901 Then
            Return True
           Else
            Return False
          End If
      Catch
         Return False
      End Try
End Sub

barx · Jul 15, 2013

True, thanks for pointing that out. In my app I have a hint showing format. That little tweak would also allow other formats too though so will ad it

GaryOCO · Jul 15, 2013

Brand new to this

Thank you Erel I will remember to post to the correct blog but I did post it in the wish list because I wish these functions were available.

I would like to thank all of you that got involved, this is my first post as a member and it is heartening to see such support.

Obviously the easy method is going to be to use the DateDialog as suggested by MC73 but I was hoping to be able to achieve these things without having to do too much programming.

After you have spent as long as I have programming in Visual Studio you get used to having your familiar tools. I guess I'll have to adjust. B4A looks great, I've had it for a week and am about to release my first app which is, in fact, a replica of one of the modules from our commercial Windows programme.

The only real problem I am experiencing is getting the views to look right on every device.

Thank you all again, I'll work with what you have suggested.

Is there an 'IsDate' function in b4a?

GaryOCO

Member

Erel

B4X founder

mc73

Well-Known Member

sirjo66

Well-Known Member

barx

Well-Known Member

Theera

Expert

barx

Well-Known Member

GaryOCO

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