title: What does ?/ mean in Ruby?
body: <p>I just stumbled across this piece of code:</p>
  
  <pre><code>if source[0] != ?/
    source = compute_asset_path(source, options)
  end
  </code></pre>
  
  <p>What's this "<code>?/</code>"? I've never seen writing strings this way.</p>
  
  <pre><code>$ irb
  2.0.0p247 :001 &gt; ?/
  =&gt; "/" 
  </code></pre>
  
  <p>Apparently it works for single characters only:</p>
  
  <pre><code>2.0.0p247 :001 &gt; ?a
   =&gt; "a" 
  2.0.0p247 :002 &gt; ?foo
  SyntaxError: (irb):2: syntax error, unexpected '?'
  </code></pre>
  
  <p>What does <code>?</code> mean?</p>