PHP在数组内查找变量

Question

I have an array called $this and in order to see what it contains i used print_r() and it happened to contain a lot of data. I need to know what variable produces the value for "user_id". It should be something like $this->user_id but i cant figure it out since its a lot of text. I would paste it here for you to see it but really, its too much. So im pasting just a little extract:

Am_Auth_User Object ( [idField:protected] => user_id [loginField:protected] => login [loginType:protected] => 0 [fromCookie:protected] => [userClass:protected] => User [plaintextPass:protected] => [session] => Zend_Session_Namespace Object ( [_namespace:protected] => amember_auth ) [user:protected] => [configPrefix:protected] => [protector:protected] => [di:protected] => Am_Di Object *RECURSION* ) [locale] => Am_Locale Object ( [locale:protected] => ja_JP ) [cacheBackend] => Zend_Cache_Backend_TwoLevels Object ( [_options:protected] => Array ( [slow_backend] => File [fast_backend] => Am_Cache_Backend_Array Object ( [_cache:protected] => Array ( [5dfbcb168a5b232b0ed52a1cb8cfb384] => 

Is there any php function that allows me to see all the variables i could use with $this array?

EDIT: I tried with

print_r(array_keys($this)); 

and

foreach(array_keys($this) as $name) {
        echo $name . "<br>";}

and

$a = array(1, 2, 3, 4, 5);
        print_r(array_map($this,$a));

But none of them produced anything. Thank you.

Answer 1

Try this in place of just the print_r():

echo '<pre>'.print_r($your_variable, true).'</pre>';

That will make it easier to read; (the true parameter returns the print_r results as a string)

Answer 2

$this is an alias of whatever class it is called from. so user_id would come from $this->user_id , which is just an alias of $user_id . it is commonly a null variable at the top of the class, ie it has to be created by the class.