Solved

VB.net check if string is a date

Posted on 2009-07-12
7
920 Views
Last Modified: 2012-05-07
Hi

I would like to check if a string is actually a date. However the issue is that I have to check that the string is actually a date in a spacific format. If the string isnt in a date certain format then I dont want to be recognised as a date.

The format of the date that Im looking to recognise is DDMMMYY
and example of this is 14Jun08

How would I do that ?

If Datestring = 14Jun08 the is date = true
If date string = 14Jun then date = NOT TRUE

I know its a wiered one but IsDate recognises the 14Jun as a valid date

Michal
0
Comment
Question by:MichMat
7 Comments
 
LVL 55

Accepted Solution

by:
Jaime Olivares earned 400 total points
ID: 24836367
you need TryParseExact method:

Dim date as DateTime
If DateTime.TryParseExact(someString, "ddMMMyy", DateTimeStyles.None, date) Then ....

Reference: http://msdn.microsoft.com/en-us/library/ms131044.aspx
0
 
LVL 59

Assisted Solution

by:Kevin Cross
Kevin Cross earned 100 total points
ID: 24836400
Just don't forget the format provider (culture info).  Jaime's solution!
Dim s As String = "14Jun"

        

        Dim d As DateTime

        Dim enUS As New CultureInfo("en-US")

        If DateTime.TryParseExact(s, "ddMMMyy", enUS, DateTimeStyles.None, d) Then

            MsgBox("Is A Date")

        Else

            MsgBox("Is NOT A Date")

        End If

Open in new window

0
 
LVL 59

Expert Comment

by:Kevin Cross
ID: 24836403
Very nice, Jaime.  I was going to do this the harder way.
Dim s As String = "14Jun"

        'Imports System.Text.RegularExpressions

        If Regex.IsMatch(s, "\d{2}[A-Za-z]{3}\d{2}") And IsDate(s) Then

            MsgBox("Is A Date")

        Else

            MsgBox("Is NOT A Date")

        End If

Open in new window

0
Highfive + Dolby Voice = No More Audio Complaints!

Poor audio quality is one of the top reasons people don’t use video conferencing. Get the crispest, clearest audio powered by Dolby Voice in every meeting. Highfive and Dolby Voice deliver the best video conferencing and audio experience for every meeting and every room.

 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 24836429
>Very nice, Jaime.  I was going to do this the harder way. '
How you will check if month abreviatures are valid? You will need a huge regex for that
TryParseExact is designed to fulfill author's requirement.
0
 

Author Closing Comment

by:MichMat
ID: 31602656
Being a novice I couldnt get Jamies to work intill the correction from mwvista1, I hope that its ok to then award the points to both as each had a part in the sucessfull solution . Thank you I would have never looked at that.
0
 
LVL 39

Expert Comment

by:abel
ID: 24836447
Just a few dots on the i if I may:

1. IsDate("35Jun08") will yield true. If you use IsDate and you want to know it is a valid date with this type of date, use the following:

If IsDate(s) AndAlso DateTime.Parse(s).Day = Val(s) Then ...

2. Reversing the logic and using AndAlso would be more efficient (IsDate is likely faster then IsMatch). But that's just a minor treat of course and hardly relevant.

3. The suggestion from jaime is missing the third parameter:

DateTime.TryParseExact(someString, "ddMMMyy", CultureInfo.InvariantCulture, DateTimeStyles.None, date)

Anyway, just my 2p. I know that you guys have given excellent suggestions already ;-)
0
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 24836535
Sorry for the missing parameter. Sometimes we don't have a machine with VS installed to fully check it.
0

Featured Post

Enabling OSINT in Activity Based Intelligence

Activity based intelligence (ABI) requires access to all available sources of data. Recorded Future allows analysts to observe structured data on the open, deep, and dark web.

Join & Write a Comment

This tutorial demonstrates one way to create an application that runs without any Forms but still has a GUI presence via an Icon in the System Tray. The magic lies in Inheriting from the ApplicationContext Class and passing that to Application.Ru…
Introduction As chip makers focus on adding processor cores over increasing clock speed, developers need to utilize the features of modern CPUs.  One of the ways we can do this is by implementing parallel algorithms in our software.   One recent…
This video discusses moving either the default database or any database to a new volume.
This demo shows you how to set up the containerized NetScaler CPX with NetScaler Management and Analytics System in a non-routable Mesos/Marathon environment for use with Micro-Services applications.

758 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

19 Experts available now in Live!

Get 1:1 Help Now