Question about declaring const pointer to const value

[linq936]

Hi,
I have the following code:

int main(){ /* line 1 */
const int i = 10; /* line 2 */
const int j = 20; /* line 3 */
/* line 4 */
int const * const p = &i; /* line 5 */
const int * const p2 = &j; /* line 6 */
/* line 7 */
(*p2)++; /* line 8 */
(*p)++; /* line 9 */

return 0;
}

Compiler does not complain line 6 and errors out on those
incremental statements of line 8 and 9.

So the declaration on line 5 and line 6 are the same? I mean "int
const * const" and "const int * const" are same?

It is a little hard to grasp how to use "const" in declaration.

Any tip?

[Richard Bos]

linq936 <li*****@gmail.comwrote:

So the declaration on line 5 and line 6 are the same? I mean "int
const * const" and "const int * const" are same?

It is a little hard to grasp how to use "const" in declaration.

Any tip?

Yes. Read the friggin' FAQ already.

<http://c-faq.com/ansi/constptrconst.html>

Richard

[CBFalconer]

linq936 wrote:

>
I have the following code:

int main(){ /* line 1 */
const int i = 10; /* line 2 */
const int j = 20; /* line 3 */
/* line 4 */
int const * const p = &i; /* line 5 */
const int * const p2 = &j; /* line 6 */
/* line 7 */
(*p2)++; /* line 8 */
(*p)++; /* line 9 */

return 0;
}

Compiler does not complain line 6 and errors out on those
incremental statements of line 8 and 9.

So the declaration on line 5 and line 6 are the same? I mean "int
const * const" and "const int * const" are same?

It is a little hard to grasp how to use "const" in declaration.

The thing that counts is which side of the * the 'const' is.
"const int *p" means p is a non-constant pointer which points at
read-only int(s). "int * const p = &x;" means p is a read-only
pointer, set to point at the variable x, and which can only be set
at this declaration point.

Try to use fixed width fonts, so as to avoid the silly widths.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net>

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