title: greater than symbol for find() method in php7 mongodb
body: <p>I am developing a php-mongodb project. I have installed the php-mongodb driver using <em>composer</em>. connectivity is working fine.</p>
  
  <p>used reference link for any guidance : 
  <em><a href="http://mongodb.github.io/mongo-php-library/tutorial/crud/#crud-operations" rel="nofollow">http://mongodb.github.io/mongo-php-library/tutorial/crud/#crud-operations</a></em>
  and <a href="http://php.net/manual/en/mongocollection.find.php" rel="nofollow">http://php.net/manual/en/mongocollection.find.php</a></p>
  
  <p>I could not find much reliable theory for php-7 except those. 
  <strong>How to fire a query with php-7 to get a result from database greater than specified number?</strong></p>
  
  <p>The code I tried is :</p>
  
  <p><code>$rs=$collection-&gt;find(['$gte'=&gt;['avg'=&gt;50]]);</code></p>
  
  <p>this is not working. The error it produced was:</p>
  
  <pre><code>Fatal error: Uncaught MongoDB\Driver\Exception\ConnectionException: unknown top level operator: $gte in /var/www/example.com/public_html/vendor/mongodb/mongodb/src/Operation/Find.php:180 Stack trace: #0 /var/www/example.com/public_html/vendor/mongodb/mongodb/src/Operation/Find.php(180): MongoDB\Driver\Server-&gt;executeQuery('training.tbl', Object(MongoDB\Driver\Query), Object(MongoDB\Driver\ReadPreference))#1 /var/www/example.com/public_html/vendor/mongodb/mongodb/src/Collection.php(437): MongoDB\Operation\Find-&gt;execute(Object(MongoDB\Driver\Server)) #2 /var/www/example.com/public_html/list.php(5): MongoDB\Collection-&gt;find(Array) #3 {main} thrown in /var/www/example.com/public_html/vendor/mongodb/mongodb/src/Operation/Find.php on line 180
  </code></pre>