PHP5 to PHP7 upgrade issue: array as object key parameter

Question

The problem is that when using PHP7 the expected result is different from PHP5, see following example with $object2.

I think that the three methods are equivalent from each other, but it seems not to be true.

It seems that in PHP7 the shortcut used with $object2 return the type of variable instead of the value.

Is there some environment configuration of PHP7 that makes it behave like PHP5 with respect to this issue?

$array1 = array();
$array1["Key"] = "Value"; 
$object1 = new stdClass();
$key1 = $array1["Key"];
$object1->Stream = new stdClass();
$object1->Stream->$key1 = 5;
echo json_encode($object1);

$array2 = array();
$array2["Key"] = "Value"; 
$object2 = new stdClass();
$object2->Stream = new stdClass();
$object2->Stream->$array2["Key"] = 5;
echo json_encode($object2);

$array3 = array();
$array3 = "Value"; 
$object3 = new stdClass();
$object3->Stream = new stdClass();
$object3->Stream->$array3 = 5;
echo json_encode($object3);

Result in PHP5:

{"Stream":{"Value":5}}

{"Stream":{"Value":5}}

{"Stream":{"Value":5}}

Result in PHP7:

{"Stream":{"Value":5}}

{"Stream":{"Array":{"Key":5}}}

{"Stream":{"Value":5}}

Answer 1

尝试将其包装在{}中

$object2->Stream->{$array2["Key"]} 

Answer 2

You can Store array index in varaible then use this variable in object

Try follwoing code

$array1 = array();
$array1["Key"] = "Value"; 
$object1 = new stdClass();
$key1 = $array1["Key"];
$object1->Stream = new stdClass();
$object1->Stream->$key1 = 5;
echo json_encode($object1);

$array2 = array();
$array2["Key"] = "Value"; 
$tmp = $array2["Key"];
$object2 = new stdClass();
$object2->Stream = new stdClass();
$object2->Stream->$tmp = 5;
echo json_encode($object2);

$array3 = array();
$array3 = "Value"; 
$object3 = new stdClass();
$object3->Stream = new stdClass();
$object3->Stream->$array3 = 5;
echo json_encode($object3);