C＃-e.KeyChar！='。' 不工作

Question

In my Windows Forms application I have a TextBox and applied to it the KeyPress event to accept just numbers. In the moment, my script is this way:

    if (!char.IsControl(e.KeyChar)
        && !char.IsDigit(e.KeyChar) 
        && e.KeyChar != '.')
    {
        e.Handled = true;
    }

The problem is that in e.KeyChar != '.' it doesn't work, my TextBox is accepting numbers and dots. I don't understand why because I say to the script that if the pressed key be different of dot (.), then doesn't input it. Some examples of values I'm receiveing are:

• x8361 - Doesn't accept
• 56491 - Accept
• 15466.5 - Accept : This is the failure. It might not accept but != doesn't do anything there.

Answer 1

Unless I am missing something, wouldn't it make more sense to check for what is acceptable rather than what isn't?

e.Handled = !(char.IsControl(e.KeyChar) || char.IsDigit(e.KeyChar) || e.KeyChar == '.');

This is by no means a complete solution however because this would still allow values like 12345.67.89. which obviously aren't numerically formatted correctly.

A more robust solution would be to use a MaskedTextBox or allow freetext but validate the entire input rather then each individual char .

Answer 2

Even better solution. With this one you can only use: 0123456789 and backspace

        if (!char.IsDigit(e.KeyChar) && e.KeyChar != '\b')
            e.Handled = true