Textbox validation in a Windows Form

Question

I want to put a validation that the user always enters a value in the textbox before submiting the form. But the check that I have put allows user to enter white spaces and

Answer 1

in NET4.0 there is a nice function

 if(string.IsNullOrWhiteSpace(textBox1.Text))
{
   //raise your validation exception
}
else {
  //go to submit
}