Text box validation not working

Question

Right now the code below tests for a blank text box. If it is blank it returns the error stated below the if statement. That works fine, but I also want it to check for wh

Answer 1

There are various Validation possibilities, maybe have a look at this.

Else you can use something like

if (txtFirstName.Text == "" && txtFirstName.Text.indexOf(" ") == -1)

which checks for whitespaces :)

Answer 2

You should check the manual:

http://msdn.microsoft.com/en-us/library/system.string.isnullorwhitespace.aspx

Indicates whether a specified string is null, empty, or consists only of white-space characters.

So use another function if you don't want any spaces (or other whitespace) to be present, like Contains or using a RegEx.

Answer 3

String.IsNullOrWhiteSpace returns true for a null string or a string that is purely whitespace For example " ".

If you do not want to allow spaces in the string ie ("B ike") test the string value for spaces using Contains(' ').

Answer 4

What about:

if (txtFirstName.Text.Contains(" "))
{
    txtFirstName.BackColor = System.Drawing.Color.Yellow;
    lblError.Text += "Please enter first name without blanks<br />";             
}  

Answer 5

I would change the following type of test:

if (txtFirstName.Text == "")

To:

if (string.IsNullOrWhiteSpace(txtFirstName.Text)) // .NET 4.0+

if (string.IsNullOrEmpty(txtFirstName.Text)) // .NET before 4.0

And for your additional test (no spaces allowed in the string):

if (string.IsNullOrWhiteSpace(txtFirstName.Text) && !txtFirstName.Text.Contains(" ")) // .NET 4.0+

if (string.IsNullOrEmpty(txtFirstName.Text) && !txtFirstName.Text.Contains(" ")) // .NET before 4.0

Note:

You will need to check that lblError.Text doesn't contain anything in order to continue to the next page, as this is what holds your errors. I can only see the DateTime test, so even if any of your txt controls have failed the validation, you still transfer.

Answer 6

if (string.IsNullOrEmpty((TextBox1.Text ?? string.Empty).Trim()))