title: C: what does the notation x=y[a=b] imply?
body: <p>I am trying to rewrite a piece of C code from another author into Python, and I came across the following type of notation:</p>
  
  <pre><code>x = y[a=b];
  </code></pre>
  
  <p>where <code>y</code> is an array and <code>a</code> and <code>b</code> are integers. At first I thought it meant something like this:</p>
  
  <pre><code>a = b;
  x = y[a];
  </code></pre>
  
  <p>But apparently it doesn't. Can anyone tell me what this expression means? Forgive me if this question is a duplicate, but it is very hard to summarise this question in a couple of searchable keywords, and I could not find anything that answers my question.</p>
  
  <p>The source of the code I am trying to rewrite: <a href="http://www.gipsa-lab.grenoble-inp.fr/~laurent.condat/download/condat_fast_tv.c" rel="nofollow">link</a></p>
  
  <p>EDIT:</p>
  
  <p>The Python-rewritten code does not work as it should (stuck in a loop), so I thought that I misinterpreted the above statement. But as several of you have suggested, it was correct in the first place. I must be something else then...</p>