PHP array_merge return null in class - php

Question

Why this code return null?
I check it but there is no error, And when i am call array merge with 2 default array Like ["x"=>"y","foo"=>"bar"] it work well!
See:
<?php
class ClassName
{
private $dataArray = array();
public function put($arr){
$this->dataArray = array_merge($arr,$this->dataArray);
return $this;
}
public function run(){
echo json_encode($this->dataArray);
}
}
$json = new ClassName();
$json->Test->LastLog = '123456789123456';
$json->Password = 'Mypassword';
$json->Dramatic = 'Cat';
$json->Things = array("HI" => 1, 2, 3);
$json->put($json)->run();

Answer 1

You Passed an object not array try like this code you got result:
$json->put((array)$json)->run();
Output is:
> {"\u0000ClassName\u0000dataArray":["Volvo XC90","BMW
> M4","MaclarenP1"],"Test":"123456789123456","Password":"Mypassword","Dramatic":"Cat","Things":{"HI":1,"0":2,"1":3},"0":"Volvo
> XC90","1":"BMW M4","2":"MaclarenP1"}
EDIT
If you want to pass the $json->Test->LastLog like this means you need to alternate you object declaration like:
$json = new ClassName();
$json->Test = array('LastLog'=>'123456789123456');
$json->Password = 'Mypassword';
$json->Dramatic = 'Cat';
$json->Things = array("HI" => 1, 2, 3);
Because in your put function is array_merge expecting array but you sent a json_object instead of array. (array) is act like json_decode...
Example: Simple Object
$object = new StdClass;
$object->foo = 1;
$object->bar = 2;
var_dump( (array) $object );
Output:
array(2) {
'foo' => int(1)
'bar' => int(2)
}