title: .NET Regex, only numeric, no spaces
body: <p>I'm looking for a regular expression that accepts only numerical values and no spaces.
  I'm currently using: </p>
  
  <pre><code>^(0|[1-9][0-9]*)$
  </code></pre>
  
  <p>which works fine, but it accepts values that consist ONLY of spaces. What is wrong with it?</p>