note 62042 modified in function.array-keys by danbrown

might be worth noting in the docs that not all associative (string) keys are a like, output of the follow bit of code demonstrates - might be a handy introduction to automatic typecasting in php for some people (and save a few headaches): <?php $r = array("0"=>"0","1"=>"1","" =>"2"," "=>"3"); echo 'how php sees this array: array("0"=>"0","1"=>"1","" =>"2"," "=>"3")',"\n-----------\n"; var_dump($r); print_r($r); var_export($r); echo "\n-----------\n",'var_dump("0","1",""," ") = ',"\n-----------\n"; var_dump("0","1",""," "); ?> OUTPUTS: how php sees this array: array("0"=>"0","1"=>"1","" =>"2"," "=>"3") ----------- array(4) { [0]=> string(1) "0" [1]=> string(1) "1" [""]=> string(1) "2" [" "]=> string(1) "3" } Array ( [0] => 0 [1] => 1 [] => 2 [ ] => 3 ) array ( 0 => '0', 1 => '1', '' => '2', ' ' => '3', ) ----------- var_dump("0","1",""," ") = ----------- string(1) "0" string(1) "1" string(0) "" string(1) " " --was-- might be worth noting in the docs that not all associative (string) keys are a like, output of the follow bit of code demonstrates - might be a handy introduction to automatic typecasting in php for some people (and save a few headaches): $r = array("0"=>"0","1"=>"1","" =>"2"," "=>"3"); echo 'how php sees this array: array("0"=>"0","1"=>"1","" =>"2"," "=>"3")',"\n-----------\n"; var_dump($r); print_r($r); var_export($r); echo "\n-----------\n",'var_dump("0","1",""," ") = ',"\n-----------\n"; var_dump("0","1",""," "); OUTPUTS: how php sees this array: array("0"=>"0","1"=>"1","" =>"2"," "=>"3") ----------- array(4) { [0]=> string(1) "0" [1]=> string(1) "1" [""]=> string(1) "2" [" "]=> string(1) "3" } Array ( [0] => 0 [1] => 1 [] => 2 [ ] => 3 ) array ( 0 => '0', 1 => '1', '' => '2', ' ' => '3', ) ----------- var_dump("0","1",""," ") = ----------- string(1) "0" string(1) "1" string(0) "" string(1) " " http://php.net/manual/en/function.array-keys.php