Date Must Be Between 1900 and 2100

[D.E.L.B.]

Okay so basically my program is a program that validates dates in this format:
DD/MM/YYYY

However, I need I guess some sort of statement (my brain is thinking an IF ELSE) to make sure that the user does not enter a date that is less than 1900 and not greater than 2100; or in other words: it must be between 1900 and 2100.

I don't suppose anyone could help me? The code I have done so far is here:

    Private Sub btnCheck_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCheck.Click
        Dim dateString, format As String
        Dim result As Date
        Dim IsValid As Boolean = False
        dateString = txtDate.Text
        format = "dd/M/yyyy"

        If format <  Then
            IsValid = False
        End If

        Try
            result = Date.ParseExact(dateString, format, System.Globalization.CultureInfo.InvariantCulture)
            IsValid = True
        Catch
            IsValid = False
        End Try
            If (IsValid) Then
                MessageBox.Show("Valid.")
            Else
                MessageBox.Show("Invalid.")
            End If
    End Sub

The validation works but the assurance of the year doesn't work.

Thanks.

[circuits2]

Start by proofreading:

format = "dd/M/yyyy"

If format < Then


Only one digit for Month? And if format is less than what? Also, format is a string, how can it be less than anything?

[dunfiddlin]

Use a DateTimePicker! You can set the min and max dates and it doesn't need any validation, making your entire code here redundant!

[D.E.L.B.]

It's a school thing that I have to do. I can't use a DateTimePicker.

@circuits2: Okay so how can I do it?

[dbasnett]

Some ideas

        Dim dtMin As DateTime = #1/1/1900#
        Dim dtMax As DateTime = #12/31/2100#

        Dim myDate As DateTime = DateTime.Now

        If myDate >= dtMin AndAlso myDate <= dtMax Then
            'valid date
        Else
            'invalid date
        End If

[D.E.L.B.]

I think you're on the right tracks, but basically I need to check the date that was entered in by the user.

[dunfiddlin]

It's a school thing that I have to do.

Ah, right. Should have led with that. Then we'd know to expect you to have to do everything the most difficult and inefficient way possible.

[D.E.L.B.]

Heh, yes, there are better ways. .

[dbasnett]

I think you're on the right tracks, but basically I need to check the date that was entered in by the user.

See http://msdn.microsoft.com/en-us/libr....tryparse.aspx

[techgnome]

you know that once you coerce the value into a date variable... it has a .Year property... and you can see if
myDateVar.Year >= 1900 andalso myDateVar.Year <= 2100


...


-tg

[D.E.L.B.]

http://puu.sh/2Km3U.jpg

This is what my window looks like. So basically the user enters the text into the textbox (it's named txtDate) and then I press the button and it validates the format of the date and if it's between 1900 and 2100.

        If result.Year >= dtMin AndAlso result.Year <= dtMax Then
            IsValid = True
        Else
            IsValid = False
        End If

I tried this here but it doesn't work either.

@circuits2: I put just the one M because this type of date is valid:
13/05/1990

As well as this:
13/5/1990

@dbasnett: If you could explain to me how I can implement that in my code it would be greatly appreciated.

[dbasnett]

Show us what you have tried using TryParse or TryParseExact

[techgnome]

If result.Year >= dtMin AndAlso result.Year <= dtMax Then

That's not what I said was it?

what I said was this:

myDateVar.Year >= 1900 andalso myDateVar.Year <= 2100

are you trying to compare the YEARS or the FULL DATE? your first post indicated that after checking to see if it's a valid date, then you need to check that the date is between 1900 and 2100 ... which are years... not dates...

-tg

[formlesstree4]

If result.Year >= dtMin AndAlso result.Year <= dtMax Then

That's not what I said was it?

what I said was this:

myDateVar.Year >= 1900 andalso myDateVar.Year <= 2100

are you trying to compare the YEARS or the FULL DATE? your first post indicated that after checking to see if it's a valid date, then you need to check that the date is between 1900 and 2100 ... which are years... not dates...

-tg

He could be labeling dtMin and dtMax as the year values perhaps? He wouldn't be able to compile it otherwise.

[techgnome]

possibly, but then he stated this "I tried this here but it doesn't work either." ... which doesn't really tell me much either... for all I know it means his fingers fell off...

-tg

[dbasnett]

http://puu.sh/2Km3U.jpg

This is what my window looks like. So basically the user enters the text into the textbox (it's named txtDate) and then I press the button and it validates the format of the date and if it's between 1900 and 2100.

        If result.Year >= dtMin AndAlso result.Year <= dtMax Then
            IsValid = True
        Else
            IsValid = False
        End If

I tried this here but it doesn't work either.

@circuits2: I put just the one M because this type of date is valid:
13/05/1990

As well as this:
13/5/1990

@dbasnett: If you could explain to me how I can implement that in my code it would be greatly appreciated.

Assuming result is a datetime and dtMin and dtMax are what I posted previously:

        If result >= dtMin AndAlso result <= dtMax Then
            IsValid = True
        Else
            IsValid = False
        End If

[D.E.L.B.]

If result.Year >= dtMin AndAlso result.Year <= dtMax Then

That's not what I said was it?

what I said was this:

myDateVar.Year >= 1900 andalso myDateVar.Year <= 2100

are you trying to compare the YEARS or the FULL DATE? your first post indicated that after checking to see if it's a valid date, then you need to check that the date is between 1900 and 2100 ... which are years... not dates...

-tg

I am trying to compare the YEARS, sorry.

[formlesstree4]

I am trying to compare the YEARS, sorry.

Then...what's the problem? There are two (maybe three, I haven't counted the entire thread) different posts that show you exactly what to do.

[D.E.L.B.]

I'm not messing you guys about but I'm overwhelmed with the amount of solutions to this problem. I haven't use DateTime.TryParse and I have no idea how to implement it. I have looked at MS' documentation but it doesn't make sense to me.

[Españolita]

Step 1. try to convert the string into a date using DateTime.TryParse

Dim DateValue as Date
If Date.TryParse (TextBoxUserInputtedDate.Text , DateValue) Then
   'Good date
Else
   MessageBox.Show ("Invalid date entered")
End If

Step 2. Now you have it as a date variable, check it is within the correct year range as per #10 Techgnome

Dim DateValue as Date
If Date.TryParse (TextBoxUserInputtedDate,DateValue) Then
    If DateValue.Year >= 1900 andalso DateValue.Year <= 2100 Then
       'This is within the range  so accept the input as correct
    Else
      MessageBox.Show ("Valid date entered but it is outside the required range")
    End If
Else
   MessageBox.Show ("Invalid date entered")
End If

[D.E.L.B.]

Thanks!

[Españolita]

I should have explained this in the last post too since you said you didn't understand the MSDN documentation. I hope my explanation makes it clearer.

If Date.TryParse (TextBoxUserInputtedDate.Text , DateValue) Then

TryParse tries to convert from one datatype to another. In the above example, you want to convert the string TextBoxUserInputtedDate.Text to a date.
If it is a valid date it sets the second variable in the argument list (DateValue) to that date.
If it is not a valid date, it returns False, therefore allowing us to do

If Date.TryParse (...) = True  Then

[D.E.L.B.]

Thank you, explained very clearly!

I just noticed something however, my DateTime has to be in the format of DD/MM/YYYY , the year formatting is correct though. I don't suppose you or anyone else could help me, please?

[formlesstree4]

You should really try and understand MSDN's documentation. However, I'll give you a hand with these two functions.