<?php
$address = array(
  'street' => 'ул. Ленина',
  'house' => '15', //дом №
  'building' => '3', //корпус
  'entry' => '', //подъезд
  'floor' => '4',
  'office' => '',
  'note' => 'код домофона: 315', //примечание
);
$result = '';
if ($address['street']) {
  $result .= $address['street'] . ', ';
}
if ($address['house']) {
  $result .= 'д. ' . $address['house'];
}
if ($address['building']) {
  $result .= ', корп. ' . $address['building'];
}
if ($address['entry']) {
  $result .= ', ' . $address['entry'] . ' под.';
}
if ($address['floor']) {
  $result .= ', ' . $address['floor'] . ' эт.';
}
if ($address['office']) {
  $result .= ', оф. ' . $address['office'];
}
if ($address['note']) {
  $result .=  ', ' . $address['note'];
}
echo $result;