Is it pointer constant or variable constant?

Question

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what is the difference between const int*, const int * const, int const *
constant pointer

Is there any difference between these two statements?

void * const sam;

and

void const *sam;

Is it just me, or are the people using `void *sam` syntax more prone to ask this question than the ones who use `void* sam`? — Lundin, Aug 21 '12 at 11:38

score 2 · Accepted Answer · answered Aug 21 '12 at 11:20

2

void * const sam;

the pointer is read-only. The qualifier is after the *.

void const *sam;

the pointee is read-only. The qualifier is before the *.

answered Aug 21 '12 at 11:20

ouah

score 0 · Answer 2 · answered Aug 21 '12 at 11:20

const int * Constant

declares that Constant is a variable pointer to a constant integer and

int const * Constant

is an alternative syntax which does the same, whereas

int * const Constant

declares that Constant3 is constant pointer to a variable integer and

Source:

score 0 · Answer 3 · answered Aug 21 '12 at 11:21

0

Yes.

After changing void to int

int * const sam;
sam = NULL; /* invalid */
*sam = 42; /* valid */

or

int const *sam;
sam = NULL; /* valid */
*sam = 42; /* invalid */

answered Aug 21 '12 at 11:21

pmg

3 Answers3