Difference between char**a and char *a[]

[no]

I hope this has not been discussed before.

But what is the
Difference between char**a and char *a[]

TIA.

 

[CBFalconer]

what is the Difference between char**a and char *a[]

At declaration time:

char **a; /* is a pointer to a pointer to char */
char *a[N]; /* needs the value of N, and is an array of char*
i.e. an array of pointer to char
N is not needed if specifically initialized */

In function prototypes:

char **a; /* is a pointer to a pointer to char */
char *a[ ]; /* doesn't need N, and no different than char** */

The results from "sizeof a" will differ in the two places for the
array like declarations. This IMO is a reason for declaring the
function parameter as char * or char ** as the case may be,
emphasizing that its value is that of a single pointer to
something.

 

[Micah Cowan]

what is the Difference between char**a and char *a[]

At declaration time:

char **a; /* is a pointer to a pointer to char */
char *a[N]; /* needs the value of N, and is an array of char*
i.e. an array of pointer to char
N is not needed if specifically initialized */

Technically, you don't need N if a is declared with internal or
external linkage; but you still need to declare it with N
*somewhere* (in the same translation unit of internal linkage; in
any translation unit otherwise), so it doesn't buy you all that much.

-Micah

 

[Eric Sosman]

I hope this has not been discussed before.

Rather than merely hoping, you could do a little bit
of research. A good place to start is the comp.lang.c
Frequently Asked Questions (FAQ) list at

http://www.eskimo.com/~scs/C-faq/top.html

But what is the
Difference between char**a and char *a[]

This is essentially Question 6.2 in the FAQ. Don't
you wish you'd checked before posting the same old
question for the umpty-leventh time?

(Although the FAQ should be the first place you look
before posting, it isn't encyclopedic: brevity has value,
and the FAQ is brief. If you can't find any discussion
of your topic in the FAQ, it's a good idea to take a look
at the archives of the newsgroup's traffic at Google, and
it's a good idea to "lurk" on a newsgroup for a few weeks
before leaping into the fray all unprepared.)

 

[Guest]

Hello Eric Sosman,

I hope this has not been discussed before.

Rather than merely hoping, you could do a little bit
of research. A good place to start is the comp.lang.c
Frequently Asked Questions (FAQ) list at

http://www.eskimo.com/~scs/C-faq/top.html

But what is the
Difference between char**a and char *a[]

This is essentially Question 6.2 in the FAQ. Don't
you wish you'd checked before posting the same old
question for the umpty-leventh time?

6.2: But I heard that char a[] was identical to char *a.

I don't think it's the same