title: Confusion about nested loops and array access
body: <p>I have some C++ I'm trying to port, and I'm confused about a couple lines and what exactly they're doing. The code is as follows. The variable <em>im</em> is a 2D float array of size num_rows by num_cols.</p>
  
  <pre><code>for(x=0; x &lt; num_cols; x++){
     float *im_x_cp = im[1]+x; //(1)
     for(y = 1; y &lt; num_rows; y++, im_x_cp+=num_cols){
        float s1 = *im_x_cp;
        //et cetera
     }
  }
  </code></pre>
  
  <p>The code marked (1) is particularly confusing to me. What part of the 2d array <em>im</em> is this referencing? </p>
  
  <p>Thanks for your help in advance.</p>