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From: mat@zeus.opt-sci.arizona.edu (Mat Watson)
Newsgroups: comp.lang.c++
Subject: Novice question about garbage creation
Message-ID: <1191@amethyst.math.arizona.edu>
Date: 15 Nov 89 16:31:53 GMT
Sender: news@amethyst.math.arizona.edu
Distribution: usa
Organization: Optical Sciences Center, Tucson, AZ
Lines: 34

I have a question about garbage creation in C++.
Suppose I define a Simple class that has a constructor, a destructor,
an assignment operator, and a friendly operator + like:

class Simple {
  double * vector;   // an array of elements
  int      n;   // the number of elements in vector
 public:
  Simple( int i ) { vector = new double[ i ]; n = i; };
  ~Simple() { delete vector; };
  Simple & operator = ( Simple & );         // assigns element by element
  friend Simple operator + ( Simple, Simple); // adds element by element
};

Now what I'd like to do inside of main() is have expressions like:

  Simple  result, x, y, z;
  /* Assume that values have been put into the elements of:    *
   * x.vector, y.vector, and z.vector .                        */
  result = x + y + z;
  
Since the + operator returns an object of the type Simple,
does the y + z part of the expression above create an unreferenced
object that just sits around and becomes garbage?

Thanks in advance.




Mat Watson
mat@zeus.opt-sci.arizona.edu [128.196.128.219]
..{allegra,cmcl2,hao!noao}!arizona!zeus.opt-sci.arizona.edu!mat
Optical Sciences Center, Univ. of Arizona, Tucson, AZ 85721, USA