What does this C statement mean?

Question

I came across this line:

void (*(*x)(void (*[10])(int *)))(int *)

Can anybody tell me what it is?

Answer 1

To break this down yourself, start from the inner most parentheses and work your way out.

1. (*[10]) <---- Array of 10 pointers
2. (*[10])(int *) <------ Array of 10 pointers to functions which has a pointer to int as its argument
3. (void (*[10])(int *)) <------ Array of 10 pointers to functions which has a pointer to int as its argument and returns void
4. (*x)(void (*[10])(int *)) <------- x is a pointer to a function which has as an argument (an array of 10 pointers to functions which has a pointer to int as its argument and returns void)

.....

I stopped partway through, but hopefully that helps.

Answer 2

cdecl is very helpful for this kind of thing. It says:

declare x as pointer to function (array 10 of pointer to function (pointer to int) returning void) returning pointer to function (pointer to int) returning void

Answer 3

You can find explanations here:

• How To Read Complicated C Declarations - does not compute
• Reading C type declarations
• C Declarations - Clockwise/Spiral Rule
• C-FAQ Question 1.21 - Complex Declarations

Answer 4

A pointer to a function which has an array of 10 pointers to functions that has int * argument and return type void as argument, and returns a pointer to a function which has int * argument and return type void.

Source