Comparing date and time

I want to write an alarm clock application that should display a certain message at a time set by the user.

How to compare system date and time wi开发者_如何学Cth the time set by users in a text box? Thanks Furqan

You can convert TextBox.Text value to a DateTime value as the following:

String dateTimeFormat = "MM/dd/yyyy hh:mm:ss tt";    
DateTime dateTimeValue = 
    DateTime.ParseExact(textBox.Text, dateTimeFormat , 
        CultureInfo.InvariantCulture);

DateTime.ParseExact Method converts the specified string representation of a date and time to its DateTime equivalent. The format of the string representation must match a specified format exactly or an exception is thrown.

You should use the intellisense feature ... but the hint is:

DateTime.Parse ....

and you need a timer, I called him "timEr" (you should name him better ....), and read the answer from Akram, he made it culture independent ....

Private Sub timEr_Tick(sender As System.Object, e As System.EventArgs) _
    Handles timEr.Tick

    timEr.Enabled = False
    If DateTime.Now >= DateTime.Parse("29.06.2011 17:29") Then
        MessageBox.Show("Time to leave the office ....")
    End If

End Sub

Your best bet would be to use System.DateTime object

Just make sure when you take a users input from a text box, that you save it in a DateTime object, then you can use the generic DateTime.Equals to compare the two.

Dim currentDateTime As New System.DateTime
Dim alarmDateTime As DateTime
currentDateTime = Date.Now
alarmDateTime = 
    New DateTime(2011, Month(Date.Now), dayInput, hourInput, minuteInput, 0)
If currentDateTime.Equals(alarmDateTime) Then
  'alarm code
End If

Something to this effect shold get the job done.

EDIT: The parse method outlined in one of the other solutions would be better for creating your alarmDateTime object than manually doing it.

Since you're using VB.NET you can use the functionality in Microsoft.VisualBasic.DateAndTime. For example, you could use DateTime.Parse (or better, .TryParse) to get a DateTime representation of the user's value, then check whether the system time is within, say, one minute of the user's time. This way, you don't need to mess with seconds.

Dim diffInMinutes As Long = 
    Microsoft.VisualBasic.DateAndTime.
        DateDiff(DateInterval.Minute, userTime, DateTime.Now)