Hướng dẫn php nullable property
The special A variable is considered to be null if:
Syntax There is only one value of type null, and that is the case-insensitive constant See also the functions is_null() and unset(). Casting to |
The special A variable is considered to be null if:
Syntax There is only one value of type null, and that is the case-insensitive constant See also the functions is_null() and unset(). Casting to |