C-language function pointers

??

A pointer to a function: #include "StdAfx.h" ? #include <stdio.h> #include "T.h" ? void Function (int i) { ???? printf ("Call Function:%d\n", i); } ? void F1 () { ???? typedef void (*pfunc) (int); ???? PFUNC PFUNC; ???? Pfunc = Function; ???? Pfunc (1);???? ???? ???? Pfunc = &Function; ???? Pfunc (2); } ? ? void F2 () { ???? typedef void (FUNC) (int); ???? ???? func* Pfunc; ???? Pfunc = Function; ???? Pfunc (3); ? ???? Pfunc = &Function; ???? Pfunc (4);???? ? } ? void T2 () { ???? F1 (); ???? F2 (); } /* Call Function:1 Call Function:2 Call Function:3 Call Function:4 Please press any key to continue . . . */ Second, function pointer disassembly: #include <signal.h> void (*signal (int signo,Void (*func) (int)))) (int); ? 1 , using typedef Disassembly typedef void (*sighandler_t) (int); sighandler_t signal (int signum,sighandler_t handler); ? 2 , using function pointers to understand Int (*p) (); P point to a parameter without any parameters, and the return value is int the function; Int (*fun ()) (); the difference between this formula and the above is Fun () Replace P , i.e. Fun () The return value is a function pointer, the function pointer ( can be seen as p) , point to one without any parameters, and return a value of int function; void (*signal (int signo,void (*FUNC) (int)))) (int); can be seen as signal () function, this function takes two parameters: one is an integer and one is a function pointer. The return value of this signal () function is also a function pointer, which points to a function with an integer parameter and a return value of void . ? This function is too complex to have any meaning in itself and is usually used typedef after the simple signal processing function. ? 3 , Case analysis 1 , instance source code ? 2 , execution procedures ? 3 , view process number ? 4 , send a signal to the process ? 5 , the process receives the signal ? ?? Three,(* (void (*) ()) 0) ()------ What is this? Do you feel the above example is too simple, not exciting? OK, let's have some excitement, look at the following example: /colgroup> 1 (* (void (*) ()) 0) (); This is the C Traps and pitfalls An example of this classic book. Not crazy, huh? Let's analyze and analyze: 1 2 3 4 The first step: void (*) (), you can see that this is a function pointer type. This function has no parameters and no return value. The second step: (Void (*) ()) 0, which is to cast 0 to the function pointer type, 0 is an address, that is, a function exists within a section of the first address of 0. Step Three: (* (Void (*) ()) 0), which is the contents of a section of memory starting at 0 address, which is the function stored in a section of the first address of 0. Fourth Step: (* (Void (*) ()) 0) (), this is a function call. Seems to be very simple, right, the above example rewrite rewrite: /colgroup> 1 (* (char** (*) (char?**,char?**)) 0) (? char?**,char?**); If there is no analysis above, Ken is afraid of not easy to see this expression to understand it. But it should be a very simple thing now. What does the reader think? ? ? Reference: 1. Anatomy of "void (*signal (int) signo,void ( int))) (int)" http:// www.51hei.com/bbs/dpj-29464-1.html ; 2. the understanding and use of C-language function pointers;

?

C-language function pointers