title: Check if character is a number in Prolog ? how to implement integer/1?
body: <p>How can I check if a character is a number in Prolog without using <code>integer/1</code> (HW)  ?</p>
  
  <p>I can use <code>atomic/1</code> , but it doesn't help me much , since it also returns true </p>
  
  <p>to anything but numbers . </p>
  
  <pre><code>2 ?- atomic(1).
  true.
  
  3 ?- atomic(asasa).
  true.
  
  4 ?- 
  </code></pre>
  
  <p>Regards</p>