How can I get a value from a multi-dimensional array using a string with combined keys?

Question

Please see my code bellow, I want to get $arr['jimmy']['age'] here. The string is jimmy.age which will be posted from ajax

<?php
$arr=array(
    'jimmy'=>array(
        'age'=>31
    )
);

$str='jimmy.age';
$keys_tree=explode('.',$str);
$x='';
foreach($keys_tree as $k=>$v){
    $x.='["'.$v.'"]';
}
echo $arr$x; //error here; how can i get $arr['jimmy']['age'] using $arr joining str ['jimmy']['age']

explain what you think $arr$x means, please. If, while you try to do so, you realise what you did wrong, there is no shame in removing this question. — Mike 'Pomax' Kamermans
– Mike 'Pomax' Kamermans, Commented Nov 28, 2013 at 3:35
You can't do it like you are trying, $x contains a string which looks like array notation. — The Alpha
– The Alpha, Commented Nov 28, 2013 at 3:39
It would with eval(), but there's too much drama attached to that function — nice ass
– nice ass, Commented Nov 28, 2013 at 3:53

nice ass · Accepted Answer · 2013-11-28 03:42:46Z

2

One way is to walk the array and keep track of each level with references:

$str ='jimmy.age';
$keys_tree = explode('.', $str);

$pointer = $arr;

while($key = array_shift($keys_tree)){

  if(!isset($pointer[$key]))
    throw new Exception(sprintf("Key %s doesn't exist", $key));

  $pointer = &$pointer[$key];      
}

echo $pointer;

answered Nov 28, 2013 at 3:42

nice ass

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