I have a boolean single check-box field. and inside my node--content-type.tpl.php Idothe following check:

      <?php if($content['field_hide_1st_line_of_the_addre']['und'][0]['value'] == 0): { ?>
        <?php print render($content['field_images']['#object']->field_location['und'][0]['street']) . t(', '); ?>
        <?php } else: { ?>
        <?php print t(''); ?>
        <?php } endif; ?>


And it returns loads of "Notice: Undefined index: und in include() (line 80 of node--content-type.tpl.php"

Any idea what is going on?

UPDATE

      <?php if (isset($content['field_hide_1st_line_of_the_addre']['und'][0]['value'])): { ?>
        <?php print render($content['field_images']['#object']->field_location['und'][0]['street']) . t(', '); ?>
        <?php } else: { ?>
        <?php print t(''); ?>
        <?php } endif; ?>

is not the doing the check correctly: the Street field disappears forallteasers,while it should only disappear for those that have the boolean check-box ticked. 

UPDATE 2
This code didn't work either. Pave me a **Parse error: syntax error, unexpected $end**

    <?php 
      if (isset($content['field_hide_1st_line_of_the_addre'][LANGUAGE_NONE][0]['value'])) :
      if($content['field_hide_1st_line_of_the_addre']['und'][0]['value'] == 0): { ;
        print render($content['field_images']['#object']->field_location['und'][0]['street']) . t(', ');
      }  endif; 
    ?>