Reading a pointer declaration

Question

# include <stdio.h>
# include <stdlib.h>    
int main(int argc, char *argv[])
{
    int daytab[2][13];
    int (*daytab)[13];
    int *px;

    return EXIT_SUCCESS;
}

I am studying pointers and having difficulty reading the int (*daytab)[13] declaration. int *px is read as px is a pointer to a int.

How do you read int (*daytab)[13]?

Already answered: http://stackoverflow.com/questions/244680/what-do-parentheses-in-a-c-variable-declaration-mean — Pacha, Dec 23 '13 at 08:06
See [this beautiful article](http://www.antlr.org/wiki/display/CS652/How+To+Read+C+Declarations). — Maroun, Dec 23 '13 at 08:07
daytab is pointer to array of 13 int. http://stackoverflow.com/questions/859634/c-pointer-to-array-array-of-pointers-disambiguation — Amit Chauhan, Dec 23 '13 at 08:08
In declaration `int (*daytab)[13]`, `daytab` is pointer to an int array of 13 elements. Read [this answer](http://stackoverflow.com/a/20120253/1673391) — Grijesh Chauhan, Dec 23 '13 at 08:11
shouldnt it be like int[13] *daytab ,to make sense as int *px? — user2688772, Dec 23 '13 at 08:13
`int int main(int argc, char *argv[])` is error removed one `int` — Grijesh Chauhan, Dec 23 '13 at 09:04

score 8 · Accepted Answer · edited May 23 '17 at 12:19

8

Apply spiral rule: is a technique known as the Clockwise/Spiral Rule which enables any C programmer to parse in their head any C declaration!

There are three simple steps to follow:

Starting with the unknown element, move in a spiral/clockwise direction; when encountering the following elements replace them with the corresponding English statements:

[X] or []
=> Array X size of... or Array undefined size of...

(type1, type2)
=> function passing type1 and type2 returning...
*
=> pointer(s) to
Keep doing this in a spiral/clockwise direction until all tokens have been covered.
Always resolve anything in parenthesis first! It will make sense;

     +---------+              
     | +-----+ |     
     | ^     | |      ( daytab)        // daytab
int (*daytab)  [13];  (*daytab)        // daytab is a pointer
 ^   ^       | |      (*daytab)[13]    // daytab is a pointer to an array of 13
 |   |       | |      int(*daytab)[13] // daytab is a pointer to an array of 13 ints 
 |   +-------+ |            
 +-------------+

Here are some answers to this question. Read them all.

edited May 23 '17 at 12:19

Community

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answered Dec 23 '13 at 08:30

haccks

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a picture is worth thousand words!! Nice expalanation in few words. – 0xF1 Dec 23 '13 at 08:34
what you say about? [http://stackoverflow.com/questions/16260417/the-spiral-rule-about-declarations-when-is-it-in-error](http://stackoverflow.com/questions/16260417/the-spiral-rule-about-declarations-when-is-it-in-error) – user2688772 Dec 23 '13 at 09:41
1

I would say to read the comments by Jonathan Leffler and Legends2k. – haccks Dec 23 '13 at 09:57
well that conversation ends nowhere – user2688772 Dec 23 '13 at 10:13
Please keep in mind that this rule is not universal. – haccks Dec 23 '13 at 10:21

Reading a pointer declaration

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