PHP Print keys from an object?

Question

I have an object BIRD and then there is [0] through [10] and each number has a subheading like "bug" or "beetle" or "gnat" and a value for each of those.

I want to print

BIRD 
    [0]
       bug = > value

I can't find out how to do this anywhere - there is talk of PUBLIC and PRIVATE and CLASS and that's where I fall off

Read this ... manual: http://php.net/manual/en/language.oop5.php — OZ_, Apr 27 '11 at 12:19

score 84 · Answer 1 · edited Jan 11 '22 at 01:58

84

You could easily do it by type casting the object:

$keys = array_keys((array)$BIRD);

edited Jan 11 '22 at 01:58

Soviut

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answered Jan 18 '13 at 17:14

brenjt

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This ends up giving me `ArrayArray to string conversion` as the result.. – Connor Leech May 07 '19 at 18:54

score 48 · Answer 2 · answered Mar 17 '14 at 18:41

48

Similar to brenjt's response, this uses PHP's get_object_vars instead of type casting the object.

$array = get_object_vars($object);
$properties = array_keys($array);

answered Mar 17 '14 at 18:41

nick

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5

Which is the more efficient approach? – John Rix Sep 22 '17 at 11:04
2

After reading https://stackoverflow.com/questions/2512212/get-object-vars-vs-cast-to-array get_object_vars is safer to use. – Clemens Tolboom May 20 '19 at 08:13

score 13 · Answer 3 · answered May 20 '19 at 12:09

If the 'object' is actually an associative array rather than a true object then array_keys() will give you what you need without warnings or errors.

On the other hand, if your object is a true object, then you will get a warning if you try use array_keys() directly.

You can extract the key-value pairs from an object as an associative array with get_object_vars(), you can then get the keys from this with array_keys():

$keysFromObject = array_keys(get_object_vars($anObject));

score 2 · Answer 4 · answered Sep 16 '20 at 11:59

Looks like array_keys might have stopped working on objects but, amazingly, the foreach construct works, at least on a php stdClass object.

$object = new stdClass();
$object->a = 20;
$object->b = "hello";
$keys = array_keys($object);
// array_keys returns null. PHP Version 7.3.3 windows
foreach($object as $key=>$value)
{
     // but this works
     echo("key:" . $key . " value:" . $value . "\n");
}

score -11 · Accepted Answer · edited Jan 18 '13 at 17:15

-11

I could be wrong but try to use array_keys using a object as parameter. I believe that is possible in php. http://php.net/manual/en/function.array-keys.php

Anyway, read about reflection.

edited Jan 18 '13 at 17:15

brenjt

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answered Apr 27 '11 at 12:25

Cloudson

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thanks I've been reading about objects and arrays for the last 3 hours. I just want to know the syntax – user723220 Apr 27 '11 at 12:44
is it print BIRD[0]=>[bug]=> or is it print_r BIRD=>0="beetle"=> = I could go on for days and days. Unfortunately there aren't any examples of this on the internet - the closest anyone comes is in this website, another similar question is asked, but he only gives the answer as $$string=>0 ? which fails PHP syntax – user723220 Apr 27 '11 at 12:51
var_dump($rss->items); I made it this far! It prints a mish mash of strings from the object, but I can't seem to continue the equation to the text node. – user723220 Apr 27 '11 at 13:18
Ok I found a workaround, in case you need values from an object, just `$var_info = print_r($rss->items, true);` where $rss is the object name and items is the child array - then use string functions to extract the text you need. – user723220 Apr 27 '11 at 13:31
If you need help printing keys from an object, check out the documentation that comes with Simple_DOM, shows you how to print the various keys in Simple_DOM objects which you can apply towards your Objects. – user723220 Apr 28 '11 at 22:57
4

array_keys works only with arrays. If you try with an object you will get a warning "Warning: array_keys() expects parameter 1 to be array, object given" – Oussama May 14 '19 at 14:51
1

I think it is wrong to use object in function that expect array. This should not be accepted answer. – zanvidmar Jul 13 '19 at 10:41

PHP Print keys from an object?

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