CODEWITHSUNDEEP
php
Derek Illchuk
Derek Illchuk

Reputation: 5658

PHP: Getting reference ID

How do I get the PHP reference ID, as is possible with the var_dump function:

// PHP 5.2.6
class Test {}

$test1 = new Test; var_dump($test1);
$test1b = $test1;  var_dump($test1b);
$test2 = new Test; var_dump($test2);

Resulting in:

object(Test)#1 (0) {}
object(Test)#1 (0) {}
object(Test)#2 (0) {}


See, var_dump can tell which references are equal without a straight-up comparison, and it prints their reference ID #1 and #2. How do I access that reference ID?

Upvotes: 4

Views: 4795

Answers (3)

mr-sk
mr-sk

Reputation: 13397

I'm not proud, but this works:

ob_start();                                                                                                                                   
var_dump($test2);                                                                                                                             
$str = ob_get_contents();                                                                                                                     
ob_end_clean();                                                                                                                               

echo substr($str, strrpos($str, '#')+1, 1);

Upvotes: 3

Maurice Kherlakian
Maurice Kherlakian

Reputation: 611

Not entirely sure if you only want to get the reference id to compare 2 instances and make sure they're equal. Should that be the case, you can use the '===' operator.

$test1 === $test1b will be true whereas $test1 === $test2 will be false.

Upvotes: 0

Pascal MARTIN
Pascal MARTIN

Reputation: 400932

I suppose a solution could be to use spl_object_hash :

This function returns a unique identifier for the object. This id can be used as a hash key for storing objects or for identifying an object.

It's not a "simple" number like what you get with var_dump, but I suppose it's better than nothing...


For instance, with this portion of code, inspired from yours :

$test1 = new Test;
$test1b = $test1;
$test2 = new Test;

echo spl_object_hash($test1) . '<br />';
echo spl_object_hash($test1b) . '<br />';
echo spl_object_hash($test2) . '<br />';

I get this output :

000000002c836d1d000000006bfbdc77
000000002c836d1d000000006bfbdc77
000000002c836d1e000000006bfbdc77

Upvotes: 10

Related Questions