Friend non member function can access private member variable also. following example help you to understand how to use friend keyword and how to access member private variables from non member function.
#include <stdio.h> class Woman{ //making it friend friend void loveWoman(); private: int age; int salary; public: char name[50]; void walk(); }; //friend function void loveWoman(){ Woman myGirlFriend; // access private member variables printf("My girlfriends age:%i \n",myGirlFriend.age); // access public member variables printf("My girlfriends age:%i \n",myGirlFriend.name); } //not a friend function void hateWoman(){ Woman myhusbandXWife; // only can access public member variables printf("My girlfriends age:%i \n",myhusbandXWife.name); } void main(){ //call friend non member function loveWoman(); //call non member function hateWoman(); }