<26> "Understanding" 10-function pointer concept and definition + "mastering" 11-function pointer use +

"Understanding" 10-function pointer concepts and definitions

  The pointer variable holding the first address of the function is the definition of the function pointer variable function pointer variable return value type ( * variable name) (parameter of the function); Declaration of function:  int  sum (int  A,int  b);----> Function pointer int  (*P1) (int          a,int   b);  //  defines a function pointer p1  // P1 can hold the return value is the int type, and there are two parameters, the type of the formal parameter is also the address of the function of type int  //   P1  = sum; // sum is the first address of the function in memory  

#include <stdio.h>floatF1 (intXinty) {    returnx+y;}intSumintAintb) {    returnA +b;}intMainintargcConst Char*argv[]) {            intx=3, y =5; ints =sum (x, y); //Defining function Pointers    int(*p) (intAintb); //Initializing function Pointersp = sum;//the first address of the SUM function//p = F1; not possible .//Note: When defining a function pointer, you do not have to write the parameter name    int(*P1) (int,int ); P1=sum; return 0;}

"Mastering" 11-function pointer use  

#include <stdio.h>intSumintXinty) {        returnx+y; }intJianintXinty) {        returnX-y; }intChengintXinty) {        returnx*y; }intChuintXinty) {    returnx/y;}intMainintargcConst Char*argv[]) {        //use of function pointers//1. Define function Pointers    int(*p) (int,int ); //2. Initialization of function pointersp = sum;//P also points to the SUM function        Switch(3) {         Case 1: P=sum;  Break;  Case 2: P=Jian;  Break;  Case 3: P=Cheng;  Break;  Case 4: P=Chu;  Break; default:             Break; }        //3. Calling functions indirectly with function pointers//(*p) (23,45);    ints = P ( at, $); printf ("%d\n", s); return 0;}

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<26> "Understanding" 10-function pointer concept and definition + "mastering" 11-function pointer use +