12. struct Rectangle with dynamic memory allocation

• 
  #include <cstring>
  
  struct Rectangle {
      int width;  // member variable
      int height; // member variable
      char* ptr_name;
  
      Rectangle()
          :
          width( 1 ),
          height( 1 ),
          ptr_name( nullptr )
      {
          set_name( "UNKNOWN" );
      }
  
      Rectangle( char const* ptr_name_, int width_  )
          :
          width( width_ ),
          height( width_ ),
          ptr_name( nullptr )
      {
          set_name( ptr_name_ );
      }
  
      Rectangle( char const* ptr_name_, int width_ , int height_ )
          :
          width( width_ ),
          height( height_ ),
          ptr_name( nullptr )
      {
          set_name( ptr_name_ );
      }
  
      ~Rectangle()
      {
          if ( ptr_name ) delete[] ptr_name;
          ptr_name = nullptr;
      }
  
      void set_name( char const* ptr_name_ )
      {
          if ( ptr_name ) delete[] ptr_name;
          int name_length = strlen( ptr_name_ ) + 1;
          ptr_name = new char[ name_length ];
          strncpy( ptr_name, ptr_name_, name_length );
      }
      //...
  };//struct Rectangle