The difference between a PHP value and a pass-through reference

The difference between a PHP value and a pass-through reference
The so-called value passing means that only the value of the object is passed to the target object, which is equivalent to copy; The system will re-open an identical memory space for the target object.
The so-called reference , that is, to pass an object's in-memory address to the target object , is equivalent to making the target object and the original object correspond to the same memory storage space . In this case, the data in memory will change if the target object is modified .

The difference between a PHP value and a pass-through reference