///////////////////////////////////////////////////////////////
//  basic1.cpp - declare class, create and use objects       //
//  ver 2                                                    //
//  Jim Fawcett, CSE687, S99                                 //
///////////////////////////////////////////////////////////////

#include <iostream>    // cout
#include <cstring>     // C style strings

class basic {

  public:
    basic(const char *inMsg);
    basic(const basic& b);
    ~basic();
    basic& operator=(const basic& b);
    void showMsg();

  private:
    char* pMsg;   // pointers need special care
                  // when copying or assigning
};

//----< constructor - stores message >-------------------------

basic::basic(const char *inMsg) {
  
  std::cout << "\n  constructing object\n";
  pMsg = new char[strlen(inMsg)+1];
  if(!pMsg)
    throw "\n  memory allocation failure\n\n";
  strcpy(pMsg,inMsg);
}

//----< copy constructor - safely copyies pointer pMsg >-------

basic::basic(const basic& b) {

  std::cout << "\n  copying object\n";
  pMsg = new char[strlen(b.pMsg)+1];
  if(!pMsg)
    throw "\n  memory allocation failure\n\n";
  strcpy(pMsg,b.pMsg);
}

//----< destructor - deallocates message storage >-------------

basic::~basic() {
  
  delete [] pMsg;
  std::cout << "\n  destroying object\n"; 
}

//

//----< assignment operator - safely assigns message >---------

basic& basic::operator=(const basic& b) {

  if(this == &b) return *this;
  delete [] pMsg;
  pMsg = new char[strlen(b.pMsg)+1];
  if(!pMsg)
    throw "\n  memory allocation failure\n\n";
  strcpy(pMsg,b.pMsg);
  return *this;
}

//----< display - show message >-------------------------------

void basic::showMsg() {
  std::cout << "  " << pMsg << "\n";
}

//----< test >-------------------------------------------------

void caller(basic b) {    // note pass-by-value

  std::cout << "\n  caller using copy of basic object\n";
  b.showMsg();
}

void main() {

  std::cout << "\n  Demonstrate Basic Class Operation "
            << "\n ===================================\n";

  basic Obj1("this is a message from first object");
  Obj1.showMsg();

  basic Obj2("this is a message from second object");
  Obj2.showMsg();

  caller(Obj1);
  caller(Obj2);

  std::cout << "\n  assigning Obj1 to Obj2:\n\n";
  Obj2 = Obj1;
  Obj2.showMsg();
}