What is the difference between these two statements:
void (*p) (void *a[],int n)
and
void *(*p[]) (void *a, int n)
3 Answers
$ cdecl void (*p) (void *a[],int n); declare p as pointer to function that expects (a as array of pointer to void, n as int) returning void; void *(*p[]) (void *a, int n); declare p as array of pointer to function that expects (a as pointer to void, n as int) returning pointer to void;
1 Comment
Chris Lutz
Does your cdecl handle parameter names, or did you just edit the I/O to be nicer to read? And if the former, where can I find a copy of this?
there is beautiful way of comprehending such type of complex declaration in Expert_C_Programming_Deep_C_Secrets_by_Peter_van_der_Linden on page 71.
According to him :
Declarations in c are boustrophedonically, i.e alternating right-to-left with left-to-right. Have a look at this snapshot
The ebook is available on google if you know how to download it.
Comments
void (*p) (void *a[],int n) p is the variable name. Remove p from the above line void ( * )(void *a[],int n) . So p is of this type. This is a pointer of a function. So p is a pointer to the function with that signature. So p is a pointer to a function which return void and takes array of 'void pointers' and int as the parameter.
void *(*p[]) (void *a, int n) [] has more precedence than *. So p is an array. remove p[] the above. So p is an array of void( * )(void *a[],int n)
So here p is an array of pointers to function which return void and takes array of 'void pointers' and int as the parameter.
1 Comment
user229044
Please stop linking to your website in your answers. Your answer should be as succinct as possible, adding a self-promoting link adds nothing to the answer.
explainin front of it, and remove the names of the arguments (a practice I do with function pointers anyway, but which C should normally parse perfectly fine). cdecl doesn't like them for no good reason I know of, but will give you the right answer if you take them out.