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<!DOCTYPE html> <html> <body> <?php function myfunction($a,$b) { if ($a===$b) { return 0; } return ($a>$b)?1:-1; } $a1=array("a"=>"red","b"=>"green","c"=>"blue","yellow"); $a2=array("A"=>"red","b"=>"GREEN","yellow","black"); $a3=array("a"=>"green","b"=>"red","yellow","black"); $result=array_udiff($a1,$a2,$a3,"myfunction"); print_r($result); ?> </body> </html>