title: PHP microtime() accuracy (zeroes at the end)
body: <p>I've got two "similar" questions about microtime accuracy.</p>
  
  <hr>
  
  <p>1) As was suggested in PHP online documentation, to get time in microseconds, I'm using a following code with microtime() function (looped):</p>
  
  <pre><code>&lt;?php
      for ($i = 0; $i &lt; 10; $i++) {
          list($usec, $sec) = explode(' ', microtime()); //split the microtime on space
          $usec = str_replace('0.', ' ', $usec); // remove the leading '0.' from usec
          echo date('YmdHis', $sec) .' '. $usec ."&lt;br&gt;"; 
      }
  ?&gt;
  </code></pre>
  
  <p>I'm getting following results:</p>
  
  <pre><code>20140526135144 72254300
  20140526135144 72255900
  20140526135144 72256500
  20140526135144 72257100
  20140526135144 72257600
  20140526135144 72258100
  20140526135144 72258600
  20140526135144 72259100
  20140526135144 72259600
  20140526135144 72260100
  </code></pre>
  
  <p>Micro means 1/100000 as far as I'm concerned. <strong>So why does microtime return 8 integers for "micro" part, and the last two are always zeros?</strong> Or I should play some lottery because I'm so happy :)?</p>
  
  <hr>
  
  <p>2) Microtime is sometimes used to generate uniqid for example. But when I run:</p>
  
  <pre><code>for ($i = 0; $i &lt; 10; $i++) {
      echo microtime()."&lt;br&gt;";
  }
  </code></pre>
  
  <p>I'm getting:</p>
  
  <pre><code>0.21820300 1401105400
  0.21821000 1401105400
  0.21821100 1401105400
  0.21821200 1401105400
  0.21821300 1401105400
  0.21821300 1401105400 // - the same as precursor
  0.21821400 1401105400
  0.21821500 1401105400
  0.21821500 1401105400 // - the same as precursor
  0.21821600 1401105400
  </code></pre>
  
  <p>How is that possible? My computer is not that fast as newer one. <strong>Is this dangerous?</strong> BTW I'm using additional "br" output, which makes the code run slower :P.</p>
  
  <hr>
  
  <p><strong>UPDATE</strong> According to comments, this is microdate(true).</p>
  
  <pre><code>1401106486.9772
  1401106486.9772
  1401106486.9772
  1401106486.9772
  1401106486.9772
  1401106486.9772
  1401106486.9772
  1401106486.9772
  1401106486.9772
  1401106486.9772
  </code></pre>
  
  <p>To cite Zorba the Greek: Total catastrophy!</p>