Differences between PHP5 and PHP7 regarding taking array elements as dynamic function names

When executing functions/methods by obtaining function/method names through variables in PHP5 and PHP7, the same code may not run due to different interpretation strategies between versions.

Example

$a = ['add', 'sub'];
 
class Test
{
　　public function add()
　　{
　　　　echo 1 + 2;
　　}
}
 
$t = new Test();
$t->$a[0]();

The above example can run normally under PHP5.6, but under PHP7 it will throw Fatal error: Function name must be a string. This is because when executing $t->$a0 under PHP5, $a[0] will be executed first, the element value will be obtained, and then the specific method of the object will be executed.

Under PHP7, $t->$a will be executed first, causing an error to be thrown and execution to be interrupted. If you need to execute it normally under PHP7, you need to modify it to $t->{$a[0]}().

For specific differences, please refer to:

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