title: How do I check in TCL if a character from a string is alphanumeric or not?
body: <p>I need to check if characters from a string, taken individually, are alphanumeric, spaces or special characters. Unable to find a definitive way of doing this.</p>
  
  <p>For example, </p>
  
  <pre><code>set str1 = "It is 5!"
  </code></pre>
  
  <p>so, my output should be:</p>
  
  <pre>I - Alphanumeric
  t - Alphanumeric
  " " - Space
  i - Alphanumeric
  s - Aplhanumeric
  " " - Space
  5 - Alphanumeric
  ! - Special Character</pre>