Re: copying an object to a char array and back

"peter koch" <>
11 Jul 2006 01:16:47 -0700
Rahul wrote:


I have following two classes
class base{
  int i;
   virtual void fun() { cout<<i<<"Base \n"; }

class d: public base{
  int j;
   void fun() { cout<<"Derived \n"; }

and the code is doing something like this.
   d d1;
   char c[100];
   bcopy((char *)&d1, c, sizeof(d));
   factory->process(c); // some factory member which accepts a char *

// Inside factory->process ()
   d *dp=reinterpret_cast<d *> (c);

Question: Is it ok to copy an object to a char array and cast it back
like this.

No it is not. In practice this can give problems even for very simple
classes that manage pointers to internal storage (std::string could do

Can there be any memory alignment problem (on a single
processor only).

Also that. There is no guarantee that c is aligned at all.

Or any other problem.

Why do yo do so in the first place? Why not simply create a new object
or copy the "normal" way? (d d2(d1) in the code above).


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