title: How can I check if a string contains only English uppercase and lovercase letters and '|' characters?
body: <p>I bag your pardon but I'm in need of any help. I must check String instance in C#. The String must contains only uppercase and lowercase English letters and '|' characters. How can I do this checking with Regex class in .NET Framework 4.5.? Suppose I got the String from Console:</p>
  
  <pre><code>String _processedString = Console.ReadLine();
  </code></pre>
  
  <p>How can I check it to according to above mentioned conditions?</p>