Some complex function prototypes like signal()

[lovecreatesbeauty]

Hello,

I'm confused by some complex function prototypes. Would you please
explain those to me in detail with C language syntax itself with your
rich knowledge & experiences. Thank you.


1. The prototype of function signal in signal.h:

void (*signal(int sig, void (*func)(int)))( int);

it's some complex to me. Please explain the C language syntax used to
make up this complex prototype.



2. And I saw another function prototype:

void interrupt (*oldhandler)() ;

-Is it legal?

-If it's a right prototype, what does identifier "interrupt" mean?
Should it be a type qualifier?



Thanks

---
lovecreatesbeau ty

[alexmdac@hotmail.com]

Re: Some complex function prototypes like signal()


lovecreatesbeau ty wrote:
[color=blue]
> I'm confused by some complex function prototypes.[/color]

"The C Programming Language" has a good section on this subject. They
provide source for a program that translates these type definitions
into english.
[color=blue]
> void (*signal(int sig, void (*func)(int)))( int);[/color]

You can simplify this:

/* Pointer to a function that takes an int and returns nothing. */
typedef void (*SIGNAL_HANDLE R)(int);

/* Simplified signal prototype. */
SIGNAL_HANDLER signal( int signal, SIGNAL_HANDLER handler );
[color=blue]
> void interrupt (*oldhandler)() ;[/color]
This is a pointer to a function which returns nothing.

[Jonathan Bartlett]

Re: Some complex function prototypes like signal()

al.h:[color=blue]
>
> void (*signal(int sig, void (*func)(int)))( int);
>
> it's some complex to me. Please explain the C language syntax used to
> make up this complex prototype.
>[/color]

The return type for signal is a function pointer that, when called takes
one int argument.

func is a function pointer that takes one int argument.

For more about function pointers, see http://www.newty.de/fpt/index.html

Jon
----
Learn to program using Linux assembly language

http://www.cafeshops.com/bartlettpublish.8640017