title: Convert array of integers to comma-separated string
body: <p>It's a simple question; I am a newbie in C#, how can I perform the following</p>
  
  <ul>
  <li>I want to convert an array of integers to a comma-separated string.</li>
  </ul>
  
  <p>I have </p>
  
  <pre><code>int[] arr = new int[5] {1,2,3,4,5};
  </code></pre>
  
  <p>I want to convert it to one string</p>
  
  <pre><code>string =&gt; "1,2,3,4,5"
  </code></pre>