What is the difference between these two C declarations?

Question

I was at an interview today, and was asked the difference between the following two declarations:

int *A[10];

and

int (*A)[10];

which I did not know. If you think I am missing some important pointer 'pointer', please let me know that too. Thanks.

http://stackoverflow.com/questions/89056/how-do-you-read-c-declarations — Markus Mikkolainen, Jun 08 '12 at 13:00
You may also find this old thread useful: [C pointers: pointing to an array of fixed size](http://stackoverflow.com/questions/1810083/c-pointers-pointing-to-an-array-of-fixed-size) — vmsnomad, Jun 08 '12 at 23:05

score 8 · Accepted Answer · answered Jun 08 '12 at 12:57

8

The first declares an array of ten pointers to int, the second a pointer to an array of ten ints.

The [] binds tighter than the *, so the first could equivalently be written

int *(A[10]);

answered Jun 08 '12 at 12:57

Daniel Fischer

Levon · Answer 2 · 2012-06-08T13:18:19.677

2

Given

int *A[10];  // an array of 10 int pointers

the relative precedences of the unary * and []makes this equivalent to

int *(A[10]);  // same

The second declaration changes that implicit ordering to

int (*A)[10]; // a pointer to an array of ten ints

edited Jun 08 '12 at 13:18

answered Jun 08 '12 at 12:59

Levon

This is about precedence, not associativity, no? – Oliver Charlesworth Jun 08 '12 at 13:01

2 Answers2