function pointer, function pointer array, function return value as function pointer

The name of the function is the first address of the function: The function pointer is defined, int (*p) (int) p is the function pointer variable name, int is the function's return value type int, and (int) is the parameter type of the function int type, note: Because of the priority so to use (*p), Otherwise, p is combined with the back () to int*p (int), which means that the return value of the P (int) function is int*Note: In the main2 () function Int (*p[]) (int, int)is a one-dimensional array, the following is wrong,

#include <stdio.h>#include<stdlib.h>intAddintAintb) {    returnA +b;}intSubintAintb) {    returnAb;}intMultiplition (intAintb) {    returnA *b;}intDiveintAintb) {    returnAb;}voidmain1 () {int(*p (int,int))(int,int);//The return value type of the P (int,int) function is int (*) (int, int) (function pointer type)System ("Pause");}voidmain2 () {intA =Ten;intb = -; //define a two-dimensional function pointer array    int(*p[]) (int,int) = {Add, sub, multiplition, dive};//" " can be written in the length of the array, or can not write, and ordinary array of the same//drop function with function pointerprintf"%d", p[1] (A, b)); //The function is called by traversing the function pointer and iterating through the array.     for(inti =0; I <4; i++) {printf ("%3d", P[i] (A, b)); }    //because * (p+i) and p[i] are equivalent, so:     for(int(**PS) (int,int) = P; PS < p +6; ps++) {printf ("%3d", (*PS)    (A, b)); }    //Int (*p) (int, int)//Int (*p[]) (int, int)//Int (**p) (int, int)System ("Pause");}voidmain33 () {//int a[3]={1,2,3}//Int (*p[]) (Int,int) ={add, Sub, Multiplition, dive}//A and P are constants, so they cannot be a=a,p=p//int *pa= (int[]) {by-means}; This is the memory on the stack.//Int (**pt) (int, int) Two-level function pointer, storing the function pointer array name//function pointer array type int (*[]) (int,int)    int(**PP) (int,int) = (int(*[]) (int,int) {Add, Sub, multiplition, dive};  for(inti =0; I <4; i++)    {        //both of these methods areprintf"%3d", Pp[i] ( -,Ten)); //printf ("%d\n", (* (pp + i) ));} system ("Pause");}voidmain44 () {//open up memory on the heap    int(**PP) (int,int) =malloc(4*sizeof(int(*) (int,int))); //assigns a value to each array element, respectively;*PP =add; * (pp +1) =Sub; * (pp +2) =multiplition; * (pp +3) =Dive; //called separately     for(inti =0; I <4; i++) {printf ("%3d", (* (pp + i)) ( -, -)); } System ("Pause");}//normal pointers, arrays and function pointers, array of function pointers//int *p int (*p) (int, int)//int*p[4] Int (*p[]) (int, int)//int **p int (**p) (int, int)//typedef simplifies writing//define variables, type + variable names first//typedef type + variable name//the variable name is the alias of the type//int X;typedefintX; //int y[10];typedefinty[Ten];//Int (*z) (int, int);typedefint(*z) (int,int);//Int (*w[]) (int, int);typedefint(*w[]) (int,int);//Int (**pp) (int, int)typedefint(**PP) (int,int); voidMain55 () {X x1;    Y Y1;    Z Z1; W W1={Add, Sub,}; PP PP1=(W) {Add, sub}; printf ("%3d",sizeof(W1)); System ("Pause");}//Int (* * x (int (*z) (int, int), int,double)) (int);//x (int (*z) (int, int), int,double)//the parameter of the X () function is int (*z) (int, int), int,double//Int (*z) (int, int) is a function pointer//Int (* *) (int) is a function return value type//the return value of x two-level function pointer, parameter, has a function pointer, int,double,//x is a function//z function pointer//Int (*p) [5];//Pointer to array//int *p[5];//array, each element is a pointer//Int (*p[5]) (int, int);//array of function pointers//Int ((* (P)) [5]) (int, int);//pointer to array of function pointersvoidMain () {int(*p[5])(int,int); int(* (*P) [5])(int,int);//pointer to an array of function pointers,//*p is a pointer, int (*[5]) (int, int) is an array of function pointers to understand,System ("Pause");}

function pointer, function pointer array, function return value as function pointer