Check if NumericUpDown is empty

if(NumericUpDown1.Text == "")
{
     // If the value in the numeric updown is an empty string, replace with 0.
     NumericUpDown1.Text = "0";
}

It might be useful to use the validated event and ask for the text property

private void myNumericUpDown_Validated(object sender, EventArgs e)
{
    if (myNumericUpDown.Text == "")
    {
        myNumericUpDown.Text = "0";
    }
}

Even if the user deleted the content of the numericUpDown control, its value still remains.
upDown.Text will be "", but upDown.Value will be the previous valid value entered.
So my way to 'prevent' the user to leave the control empty, on the onLeave event, I set:

upDown.Text = upDown.Value.ToString();