Best way of iterating over object member fields in PHP?

Question

I came across a bug in some of my code, where I do something like the following:

$obj = new MyObject();

foreach ($obj as $key=>$value)

{    
 echo $key;
}

Note that I don't use $value in the loop - I'm only doing processing based on the field name.

Now my IDE flags this unused variable as a hint, so (on autopilot) I changed it to be

$obj = new MyObject();
foreach (array_keys($obj) as $key)
{
 echo $key;
}

Which removes the hint, and looks like the right sort of thing. Of course this doesn't work: "array_keys() expects parameter 1 to be an array, object found".

So what is the correct way to list the field names of an object?

Comments

Two ways depending on whether you want to get them from the class definition or what the object actually contains:
* http://php.net/get-class-vars
* http://php.net/get-object-vars

Answer 1

You could use get_object_vars
http://php.net/manual/en/function.get-object-vars.php

So something like the following may work

$obj = new MyObject();
foreach (array_keys(get_object_vars($obj)) as $key)
{
 echo $key;
}