Using TryParseExact with WindowsForms Textbox

Question

I am currently trying to validate a textbox, so only letters (a-Z) can be entered, with the use of TryParseExact.

I have a code to check a time, although could someone demonstrate how this could be done with letters only.

My code is as follows:

private void textBox2_Validating(object sender, CancelEventArgs e)
{
    DateTime dateEntered;

    if (DateTime.TryParseExact(textBox2.Text, "HH:mm", System.Globalization.CultureInfo.CurrentCulture, System.Globalization.DateTimeStyles.None, out dateEntered))
    {

    }
    else
    {
        MessageBox.Show("You need to enter valid 24 hour time");
    }
}

What do you mean with letters only? No numbers? No spaces or punctuation? — agent-j
– agent-j, Commented Jun 20, 2011 at 17:07

dtb · Accepted Answer · 2011-06-20 16:56:22Z

3

This checks if all characters in a string s are a letter:

bool result = s.All(ch => char.IsLetter(ch));

3 Comments

Dan Over a year ago

How could I implement this into my current method?

dtb Over a year ago

@Dan: Are you asking how to combine a boolean expression and if?

dtb Over a year ago

@Dan: if-else (C# Reference)

Davide Piras · Accepted Answer · 2011-06-20 16:57:08Z

0

You should not use any try-parse method because checking if a string only contains a-Z chars is not the same as parsing a date or a number.

I think you can use regular expressions to validate the input.

answered Jun 20, 2011 at 16:57

Davide Piras

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