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<!DOCTYPE html> <html> <body> <?php function myfunction_key($a,$b) { if ($a===$b) { return 0; } return ($a>$b)?1:-1; } function myfunction_value($a,$b) { if ($a===$b) { return 0; } return ($a>$b)?1:-1; } $a1=array("a"=>"red","b"=>"green","c"=>"blue"); $a2=array("a"=>"red","b"=>"green","c"=>"green"); $result=array_udiff_uassoc($a1,$a2,"myfunction_value","myfunction_key"); print_r($result); ?> </body> </html>