Classes with External Resources

• Class constructor prepares a new object by creating an environment in which member functions operate.
• When this environment acquires external resources, that resource must be handled carefully whenever the object is copied and also when the object goes out of scope.
• Example:

class IntArray
{
  public:
    IntArray ( size_t size = 10 , int ivalue = 0 );
    ...
  private:
    size_t size_;
    int *  data_;
} ;

IntArray::IntArray (size_t size, int ivalue) : size_(size) , data_(nullptr)
{
  data_ = new int [size_];  // don't forget to check for failed allocation
  for (size_t i = 0; i  < size_; ++i)
    data_[i] = ivalue;
}