PHP:

 <div class=shadow-box> <h3 class=title style=font-size:20px> <?php if($pet["pet_cat"] == 2): ?> <?php echo $pet["pet_name"]; ?> <?php else: ?> <?php echo "Please Help me"; ?> <?php endif; ?> </h3> <p class=subtitle> <?php if($pet["pet_cat"] == 2): ?> <?php echo $pet["english"]; ?> <?php else: ?> <?php echo $pet["dog_english"]; ?> <?php endif; ?> <div class=image> <a href=<?php echo base_url(); ?>index.php/Pet/view/<?php echo $pet["petid"];?> id=listinglink target=_blank><img src=<?php $img = unserialize($pet["img"]); echo base_url();?>assets/img/<?php echo $pet["pet_hidenum"]."/".$img[0]?> class=img-responsive id=centerimg></a></div><div class="clearfix quick-info"><div class=left><p><span class=icon style=font-size:12px><img src=images/location.png alt=""></span><?php echo $pet["reg_postal"].",".$pet["reg_city"].",".$pet["reg_country"]?><?php if($pet["showtel"] == "Yes"):?><p><span class=icon><img src=images/phone.png alt=""></span><?php $mobile_phone_number = unserialize($pet["mobile_phone_number"]); echo $mobile_phone_number[0];?><?php endif;?><?php if($pet["pet_type"] == "Lost"):?><p id=rewardon><span class=icon><img src=images/reward.png alt=""></span>Reward:€ (EUR)</div><?php endif;?><div class=right><p style=margin-top:14px><img src=images/mini_logo.png alt=""style=width:95px><p>37070 Days Ago</div></div></div>

Error:

 Use of undefined constant php - assumed 'php'

¿Por qué muestra el error Uso de una constante indefinida? Revisé dos veces pero no encontré nada malo en mi código. Tu ayuda es apreciada...............