// DEM_CON.CPP -- demostrate use of const

#include <iostream.h>

class DC {
  public:
    void mf1(const DC &dc) { cout << "inside mf1" << endl; }
    void mf2(DC &dc)       { cout << "inside mf1" << endl; }
    void mf3() const       { cout << "inside mf2" << endl; }

//  won't compile because const dc returned by ref
//  DC&  mf4(const DC& dc) { cout << "inside mf4" << endl; return dc; }

//  This compiles !!! with only a warning
    friend void ff1(const DC &dc) { cout << "inside ff1" << endl; }
    friend void ff2(DC &dc)       { cout << "inside ff2" << endl; }
};

void main() {

  DC dc;
  const DC cdc;
//  cdc.mf1(dc);     // won't compile - non-const function on const object
//  cdc.mf2(dc);     // compiles - warning non const func called on const
//  cdc.mf2(cdc);    // compiles - warning about tempory used to initialize
  dc.mf3();        // won't compile - non const using const mf
  cdc.mf3();       // compiles
  ff1(dc);         // won't compile - type mismatch
  ff1(cdc);        // compiles
  ff2(dc);         // won't compile - type mismatch
//  ff2(cdc);        // warns only about structure passed by value!!
}