Constant Pointer:

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• Constant Pointer
• Has to be initialized when it is declared.
• After it is initialized, this pointer can not be
  
• redirected (i.e., a constant pointer cannot be
• assigned a value), but the variable that this
• pointer points to can be modified.
• Can be assigned to an ordinary pointer.
• Pointer to Constant
• May point to a non-constant variable, but this
• variable cannot be modified through this
• pointer. For instance, let p be a pointer to
• const int, and it points to an int variable x.
• Then x is, of course, not a constant, but p
• is a constant, although they refer to the
• same memory location.
• An ordinary pointer can be assigned to a pointer
• to constant, but a pointer to constant cannot
• be assigned to an ordinary pointer.

Examples pc y pc pp // OK, int is
converted to const int pp x // invalid,
cannot convert const int to int pp pc //
invalid, cannot convert const int to int pp
cp // OK, int const is converted to int pc
y // invalid, assignment to constant
z 5 // OK, although it is pointed to by a
pointer to constant z x // OK, const int is
converted to int pc 5 // invalid, assignment
to constant cp x // OK, assignment to
pointee cp x // invalid, redirection of
constant pointer cpc x // invalid,
redirection of constant pointer cpc x //
invalid, assignment to constant