CODEWITHSUNDEEP
c#.netwindows
Jay
Jay

Reputation: 185

C# - Using Regex's with TextBox.Validating

Instead of using if (numberEntered < 1 || numberEntered > 24), is it possible to use a regex to check whether the field is in a 24 hour clock format e.g. 23:00. 

private void textBox4_Validating(object sender, CancelEventArgs e)
{
    {
        int numberEntered;

        if (int.TryParse(textBox4.Text, out numberEntered))
        {
            if (numberEntered < 1 || numberEntered > 28)
            {
                MessageBox.Show("You have to enter a number between 1 and 28");
                textBox4.Text = 5.ToString();
            }
        }
        else
        {
            MessageBox.Show("You need to enter an integer (number)");
            textBox4.Text = 5.ToString();
        }
    }

Upvotes: 1

Views: 649

Answers (4)

David Hall
David Hall

Reputation: 33153

As Jonas says, using DateTime.TryParse is preferable to using a regex, however, you might want to consider using a DataTimePicker control.

If you set the Format property to Custom and then set the CustomFormat property to HH:mm you will get a textbox like control that restricts input to 24hr time.

Finally, if you set ShowUpDown to true you will no longer have the calendar visible but have an updown instead.

Upvotes: 0

Jonas Elfstr&#246;m
Jonas Elfstr&#246;m

Reputation: 31428

string time = "23:00";
var time24 = new Regex(@"^(20|21|22|23|[01]\d|\d)(([:][0-5]\d){1,2})$");
bool is24hTime = time24.IsMatch(time);

Would probably work but I think that DateTime.TryParse is the way to go.

Upvotes: 2

Jeff
Jeff

Reputation: 14279

Is it possible? Yes. Is it preferred? No. It is better to parse the string into an integer and validate as you are currently doing then to use a regular expression. Regular expressions weren't really made to do what you are asking them to so the resulting regex would be awkward.

Upvotes: 1

Tomas Voracek
Tomas Voracek

Reputation: 5914

Use http://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox.aspx

Upvotes: 0

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