[RESOLVED] Checking String Format

[Brian M.]

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.

[jmcilhinney]

First up, don't use this:

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

Use this:

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

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.

[.paul.]

you could use regex to validate it

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)

[dbasnett]

@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.

[Brian M.]

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.

[VBDT]

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.

[Brian M.]

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

[VBDT]

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

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

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

[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.

[VBDT]

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.

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

[Brian M.]

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

[dbasnett]

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