title: make limitation for random class in c#
body: <p>I want to make limitation for random class in c# like generate random variables from 2 ranges without repeat it? 
  example :</p>
  
  <pre><code>Xpoints[i] = random.Next(0, 25);
  Ypoints[i] = random.Next(0, 12);
  </code></pre>
  
  <p>where 25 we 12 is image dimension so I need all pixels in this image but random ? any suggestion if I use this code i didn't get some pixels and some pixels repeated </p>