Deleting number from text box produces error

Question

I have a TextBox in which I wanna place a number, the program is supposed to read it, by converting it into a decimal, however, after performing the needed maths with the number, if I delete it from the TextBox, it immediatly produces an error:

Format exception was unhandled ( input string in a incorrect format)

this happens on the line on which I try to convert the text into a decimal

private void readW_TextChanged(object sender, EventArgs e)
{
    string _W = readW.Text;
    _Wd = Convert.ToDecimal(_W);
}

Answer 1

You get

Format exception was unhandled ( input string in a incorrect format)

because string.Empty cannot be converted to a decimal.

You can use TryParse to inform you if parsing fails:

bool success = decimal.TryParse(_W, out _Wd);
if (success) {
    // Use the result
}
else {
    // Depending on your needs, do nothing or show an error
}

Note that _W being string.Empty may be a condition you want to ignore, while other parse failures might warrant an error message. If so, your else might look like

else {
    if (!string.IsNullOrEmpty(_W)) ShowAnErrorMessageSomehow();
}