Question

I would like to know if a friend function can change private data in the class without using a

pointer and sending out the object.

I mean does a friend function have access like a member function?

For Example:

    class myinfo {
       private:
          char name[20];
          int id;
          float income;         
       public:
          void showInfo(void);
          myinfo(void);
          friend void updateInfo(myinfo);

      int main ( ) {

      myinfo j;
       updateInfo(j); // calling the friend function

   return 0;
}

    void updateInfo(myinfo c) {
       strcat(c.name, ":updated");
       c.id++;
       c.income += 1.1;

Answer 1

Yes, but not the way you’ve written it… If you want the function to modify the passed in object, accept a reference rather than by value…

It appears you’ve not learned about references in c++.

// Declaration of function in class
friend void updateInfo(myinfo&);

implementation

void updateInfo(myinfo& c)
{
  strcat(c.name, ":updated");  // now modifying passed in instance of c.
  c.id++;
  c.income += 1.1;
}

Btw. on a side note, prefer to use std::string and also learn about rule of three (specially for non-trivial classes such as this).