find space in space in login name

can anybody tell me the way to check whether the user name entered is contained space or not. using asp.net membership control, thanks

It will be good if you let us know the exact requirement. anyways, space checking can be done this way
if(TextBox1.Text.IndexOf(string.Empty) > 0) 
lblError.Text="space present" ;
SHASHANK BHIDE
CAPGEMINI INDIA
"THE ROAD TO SUCCESS IS ALWAYS UNDER CONSTRUCTION MARK MY RESPONSE AS ANSWER TO HELP ME BUILD IT :)"

 Instead of using string.Empty, it should be 
if (TextBox1.Text.IndexOf(" ") > 0) 
{
  lblError.Text="space present";
}
 
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YES YES, U R RIGHT, MY MISTAKE, HOW SPACE CAN BE EMPTY 
SHASHANK BHIDE
CAPGEMINI INDIA
"THE ROAD TO SUCCESS IS ALWAYS UNDER CONSTRUCTION MARK MY RESPONSE AS ANSWER TO HELP ME BUILD IT :)"