On the use of constant pointer and pointer constant -- exercise (record)

Constant pointer ：

Definition ：  A constant pointer is essentially a pointer , But the object pointed to by this pointer is a constant .
Statement ： int const *  a;    or    const int * a;

notes ：const int   i=3;         int const * a=&i;     const int  j = 4;     a=&j;    // legal

The object pointed to by the constant pointer cannot be modified by this pointer , But because the constant pointer itself is a variable , therefore , Can be reassigned .

constant pointer ：

Definition ：  A pointer constant is essentially a constant , But the value of this constant is a pointer .
Statement ： int * const a;

notes ：const int   i=3;         int * const a= &i;     *a = 4;  // legal  

  The value of a pointer constant is a pointer , Because this value is constant , So the pointer itself cannot be changed . however , The contents of the pointer can be changed .