Constant pointer and constant pointer to a constant and to a constant

(1) pointer to a constant: A pointer variable pointing to a constant. Const int * P = & X; * P content cannot be modified, however, the pointer P can point to another address, which is the same as int const * P.

(2) constant pointer: int * const P = & X pointer itself is a constant, fixed to a variable, so P is not variable, but * P is variable

(3) A constant pointer to a constant: const int * const P = & X. The pointer P always points to X and cannot be used to modify the content of the address it points.

Constant pointer and constant pointer to a constant and to a constant