c++ - Difference between Function pointer and passing pointers -

i have these codes...

#include <iostream> using namespace std;   int * function (int  a, int  b);   int main()  { int = 2; int b = 7; int * x = &a; int * y = &b;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  function (a , b); cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  function (a ,  b); cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  system ("pause"); return 0; }  int * function (int  a, int  b) {     int pom;       pom =  a;      = b;       b = pom;  } 

this 1 function pointer , not change variables. dont know why, , means fucntion pointer. why kind of pointers useful ?

versus

  #include <iostream>  using namespace std;    int  function (int * a, int * b);   int main()  { int = 2; int b = 7; int * x = &a; int * y = &b;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  function (&a , &b); cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  function (&a , & b); cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  cout << endl << endl;  cout << << "   " << *x << endl; cout << b << "   " << *y << endl;  system ("pause"); return 0; }  int  function (int * a, int * b) {     int pom;       pom =  *a;      *a = *b;       *b = pom;         } 

this ordinary passing pointers, change variables books learn. interested how use passing pointer expamle arrays.

you mixing concepts, none of funtion pointers

int * function (int  a, int  b); int  function (int * a, int * b); 

this:

int * function (int  a, int  b); 

is function takes value 2 ints , returns pointer int

and this

int  function (int * a, int * b); 

is function takes 2 pointers ints , returns int