[RESOLVED] Checking String Format

Hello. I am trying to write an alarm clock program with vb express 2008, but I've run into a problem that I need help with. I retrieve a time from a text box from the user, how do I make sure they have the correct format so I can match it up with a time that is using this format: Format(Now, "hh:mm.ss tt"). It seems simple, but it has me stumped right now. How do I tell if a part of a string is numeric or not? Any help would be appreciated.

First up, don't use this:

Code:

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Format(Now, "hh:mm.ss tt")

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Use this:

Code:

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Date.Now.ToString("hh:mm.ss tt")

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Secondly, don't use a TextBox. Use a DataTimePicker and then you don't have to do anything. You get a DateTime value from the DTP's Value property.

If you really did need to convert a string to a time, you'd use TimeSpan.TryParse, DateTime.TryParse or DateTime.TryParseExact.

you could use regex to validate it

vb Code:

Dim timeStr As String = "02:59.50 PM"
Dim rxTime As New Regex("^(0[1-9]:[0-5][0-9].[0-5][0-9]|1[0-2]:[0-5][0-9].[0-5][0-9]) (AM|PM)$")
MsgBox(rxTime.Match(timeStr).Success)

@brian - jmc said "If you really did need to convert a string to a time, you'd use TimeSpan.TryParse, DateTime.TryParse or DateTime.TryParseExact." They will all give valid / invalid indications of time.

BTW - i live in jefferson city.

Thanks for the responses, I think I have a solution to the input format problem, but I would still like to know a way to make sure part of a string is a numeric value. I would parse the string using the mid function, but what kind of check can I run on the parsed part to make sure it's a number value? Thanks for your help.

I would still suggest you to use the Jmc’s suggestion but if you want to check the string for numeric values than you need to write a method to do that. You could loop through the chars of the string and check if they are numeric or not.

Ok, but what do I compare them to? I mean what do I use to distinguish between numeric or non numeric?

Quote:

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Originally Posted by Brian M.

Ok, but what do I compare them to? I mean what do I use to distinguish between numeric or non numeric?

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The Char data type has a method “IsDigit” that returns a Boolean value that indicates if the character is digit or not.

Code:

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Dim myString As String = "Text2"
For Each ch As Char In myString
    If Char.IsDigit(ch) Then
        'Is digit
    Else
        'Isn't digit
    End If
Next

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That's what I was looking for. Thanks alot. I just wanted a simple interface to wake me up in the morning. I have an alarm clock I made with just basic that uses wav files and random numbers, but its a console app, I wanted an alarm gui. Keep an eye out in code-bank for this alarm clock.

Quote:

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Originally Posted by Brian M.

That's what I was looking for. Thanks alot. I just wanted a simple interface to wake me up in the morning. I have an alarm clock I made with just basic that uses wav files and random numbers, but its a console app, I wanted an alarm gui. Keep an eye out in code-bank for this alarm clock.

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Looks nice, I have also started a desktop alarm clock and didn’t finish yet.

Its amazing how hard something simple like an alarm clock can be to make.

if you had used the datetimepicker for your input instead of a textbox it would have been easier.