title: Two variables in a 'for' loop in C
body: <p>I am writing some code where I need to use two variables in a <code>for</code> loop. Does the below code seem alright?</p>
  
  <p>It does give me the expected result.</p>
  
  <pre><code>for (loop_1 = offset,loop_2 = (offset + 2); loop_1 &gt;= (offset - 190),loop_2 &lt;= (190 + offset + 2); loop_1--,loop_2++)
  {
      if (  (*(uint8_t*)(in_payload + loop_1) == get_a1_byte(bitslip)) &amp;&amp;
           ((*(uint8_t*)(in_payload + loop_2) == get_a2_byte(bitslip)))
         )
      {
            a1_count++;
      }
  }
  </code></pre>
  
  <p>But I am getting a compiler warning which says:</p>
  
  <blockquote>
    <p>file.c:499:73: warning: left-hand operand of comma expression has no effect</p>
  </blockquote>
  
  <p>What does this mean?</p>