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  1. <?php
  2.  
  3.     $x = undefined;
  4.     $y = undefined;
  5.     $$x = "a";
  6.  
  7.     echo $$x;  // -> "a"
  8.     echo $$y;  // -> "a"
  9.  
  10.     $$y = "b";
  11.  
  12.     echo $$x;  // -> "b"
  13.     echo $$y;  // -> "b"
  14.  
  15.     echo ${"undefined"}; // -> "b"
  16.  
Success #stdin #stdout #stderr 0.02s 20568KB
comments (?)
stdin 
Standard input is empty
stdout 
aabbb
stderr 
PHP Notice:  Use of undefined constant undefined - assumed 'undefined' in /home/rdMEa3/prog.php on line 3
PHP Notice:  Use of undefined constant undefined - assumed 'undefined' in /home/rdMEa3/prog.php on line 4
https://ideone.com/8Fvkk1
language:
PHP (php 7.3.5)
created:
10 years ago
visibility:
public

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