Convert JSON String to Array in PHP

<?php 

$str = '{"id":"st01","name":"Name 1","age":20}';
$student = json_decode($str, true);
print_r($student);
echo '<br>id: '.$student['id'];
echo '<br>name: '.$student['name'];
echo '<br>age: '.$student['age'];

?>       
    

Output

Array ( [id] => st01 [name] => Name 1 [age] => 20 )
id: st01
name: Name 1
age: 20