title: In C - check if a char exists in a char array
body: <p>I'm trying to check if a character belongs to a list/array of invalid characters.</p>
  
  <p>Coming from a Python background, I used to be able to just say :</p>
  
  <pre><code>for c in string:
      if c in invalid_characters:
          #do stuff, etc
  </code></pre>
  
  <p>How can I do this with regular C char arrays?</p>