What is the difference between char * const and const char *?
The difference is that const char *
is a pointer to a const char
, while char * const
is a constant pointer to a char
.
The first, the value being pointed to can't be changed but the pointer can be. The second, the value being pointed at can change but the pointer can't (similar to a reference).
There is also a
const char * const
which is a constant pointer to a constant char (so nothing about it can be changed).
Note:
The following two forms are equivalent:
const char *
and
char const *
The exact reason for this is described in the C++ standard, but it's important to note and avoid the confusion. I know several coding standards that prefer:
char const
over
const char
(with or without pointer) so that the placement of the const
element is the same as with a pointer const
.
To avoid confusion, always append the const qualifier.
int * mutable_pointer_to_mutable_int;
int const * mutable_pointer_to_constant_int;
int *const constant_pointer_to_mutable_int;
int const *const constant_pointer_to_constant_int;