c++

what do you mean by public and private in c++?

 

I think Public means any body of function can access member function and data member
private means only class body can access member function and data memb

 

I'd add that you can use private members to "hide" data types from multiple folks working on a project. Perhaps group A devises the class while group B is only given the function members.

Code:

class foo {

   public : foo(const int &init_value = 0) { 
                 // constructor
                 private_data.int_val = init_value; 
              }

              void setInt(const int &new_value) { 
                 // accessor member function
                 private_data.int_val = new_value; 
              }

              int some_value; // directly accessible to each object of foo

   private : typedef struct {
                   int int_val;
               } pd;
 
               pd private_data; // only accessible by accessor member 
                                // functions
};

int main() {

   foo test; // instantiate an object
   test.setInt(50); // use accessor function to modify
                    // private data

   test.some_value = 10;  // ok; data member is public

   return 0;
}

If group B were only given the member functions, they'd never know that setInt was actually modifying a structure.

HTH