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  1. <?php
  2.  
  3. $array = array(
  4. 	'null'      => NULL,
  5. 	'empty'     => '',
  6. 	'zero'      => 0,
  7. 	'space'     => ' ',
  8. 	'character' => 'X',
  9. 	'true'      => TRUE,
  10. 	'false'     => FALSE,
  11. );
  12.  
  13. print_r('<table><tr><td>'.implode('</td><td>',array(
  14. 	'Key', 'array_key_exists()', 'isset()', 'empty()', 'is_null()'
  15. )).'</td></tr>');
  16.  
  17. // We merge in 'undefined' so we have it as a key.
  18. foreach(array_merge($array, array('undefined' => 1)) as $key => $dont_use) {
  19. 	print_r('<tr><td>'.implode('</td><td>',array(
  20. 		'$array[\''.$key.'\']',
  21. 		var_export(array_key_exists($key, $array),true),
  22. 		var_export(isset($array[$key]),true),
  23. 		var_export(empty($array[$key]),true),
  24. 		var_export(is_null($array[$key]),true)
  25. 	)).'</td></tr>');
  26. }
  27.  
  28. print_r('</table>');
Success #stdin #stdout #stderr 0.01s 20568KB
comments (?)
stdin 
Standard input is empty
stdout 
<table><tr><td>Key</td><td>array_key_exists()</td><td>isset()</td><td>empty()</td><td>is_null()</td><td>=== NULL</td></tr><tr><td>$array['null']</td><td>true</td><td>false</td><td>true</td><td>true</td><td>true</td></tr><tr><td>$array['empty']</td><td>true</td><td>true</td><td>true</td><td>false</td><td>false</td></tr><tr><td>$array['zero']</td><td>true</td><td>true</td><td>true</td><td>false</td><td>false</td></tr><tr><td>$array['space']</td><td>true</td><td>true</td><td>false</td><td>false</td><td>false</td></tr><tr><td>$array['character']</td><td>true</td><td>true</td><td>false</td><td>false</td><td>false</td></tr><tr><td>$array['true']</td><td>true</td><td>true</td><td>false</td><td>false</td><td>false</td></tr><tr><td>$array['false']</td><td>true</td><td>true</td><td>true</td><td>false</td><td>false</td></tr><tr><td>$array['undefined']</td><td>false</td><td>false</td><td>true</td><td>true</td><td>true</td></tr></table>
stderr 
PHP Notice:  Undefined index: undefined in /home/LA9sU0/prog.php on line 24
PHP Notice:  Undefined index: undefined in /home/LA9sU0/prog.php on line 25
https://ideone.com/2mWZ7t
language:
PHP (php 7.3.5)
created:
10 years ago
visibility:
secret

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