Getting IDs without printing them?

There’s something wrong in this code:

$myQuery = new WP_Query();
$myQuery->query(‘post_type=page&meta_key=mood&meta_value=frustrated’);
$myArray = array();
while ($myQuery->have_posts())
{
the_post();
global $post;
$myArray[] = $post->ID;
}
echo count($myArray);

On the last line in the while block, I get this error:

Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 35 bytes)