3v4l.org

run code in 300+ PHP versions simultaneously
<?php $arr = array( array( 'id' => 1, 'user_name'=>'test1' ), array( 'id' => 2, 'user_name'=>'test2' ), array( 'id' => 3, 'user_name'=>'test3' ) ); $arr2 = array( array( 'id' => 1, 'shop_name'=>'shop1' ), array( 'id' => 5, 'shop_name'=>'shop2' ), array( 'id' => 3, 'shop_name'=>'shop3' ) ); foreach($arr as $key => &$value) { $value['shop_name']=''; } unset( $value ); foreach($arr as $k2 =>&$v2) { foreach($arr2 as $k =>$v) { if($v2['id'] == $v['id']) { $v2['shop_name'] = $v['shop_name']; } } } print_r($arr);

preferences:
51.3 ms | 402 KiB | 5 Q