Deep Copy vs Shallow copy

An example would be

class A
{
 string s;
};
A a;
A b;
a=b; //deep copy
memcpy(&a,&b,sizeof(A)); // shallow copy

Also check out http://www.devx.com/tips/Tip/13625 ("Deep Copy and Shallow Copy" - that's where the example comes from) and http://en.wikipedia.org/wiki/Object_copy for further information

Thanks Jkr.  Sorry, I wasn't clear enough.  I just want to understand how we eliminate shallow copy using a copy constructor.  I read that the default copy constructor does a shallow copy.  

Well, in that case, maybe the example should be a bit more complex, e.g.

class A
{
 // members
 string s;
 vector<string> vs;

  A& assign(const A& a) // helper to be used by both the copy ctor and assignment operator
  {
    // copy each member
    s = a.s;
    vs = a.vs;
  }

public:

  A(const A& a) // copy constructor
  {
    assign(a);
  }

  A& operator=(const A& a) // assignment operator
  {
    return assign(a);
  }

};

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For example, you have a pointer in a structure(or class)
struct node
{
       char* ptr;
};
In copy constructor, if you copy the ptr itself, it's a shallow copy. If you allocate a new memory, copy the content of the string, that's a deep copy.  

pls check this link...

http://bytes.com/topic/c/answers/569803-deep-copy-vs-shallow-copy

The ShallowCopy and DeepCopy classes differ in that the DeepCopy class contains a copy constructor. Here is the output when running this program:

 *sc.pb 43   *sc2.pb 43
 *dc.pb 22   *dc2.pb 44

Notice that when we execute the line:
     *sc2.pb = 43;
then *sc.pb has the same value. If this is desired, then fine. But if you require that the value pointed to by sc.pb be maintained independent of operations on sc2, then a deep copy is in order. The DeepCopy class copy constructor allocates its own memory for pb, and changing one object of DeepCopy does not affect the value in another object of DeepCopy.

#include <iostream>
using namespace std;

class ShallowCopy {
public:
	ShallowCopy( int aa, int* pp): a(aa), pb(pp) {}

	int a;
	int * pb;
};

class DeepCopy{
public:
	DeepCopy( int aa, int* pp): a(aa), pb(pp) {}
	DeepCopy( const DeepCopy &d ) {
		this->a = d.a;
		this->pb = new int(*d.pb);
	}

	int a;
	int * pb;
};

void main() {
	int * pIntDeep   = new int;
	int * pIntShallow = new int;

	*pIntShallow = 22;
	*pIntDeep   = 22;

	ShallowCopy sc( 2, pIntShallow );
	ShallowCopy sc2(sc);
	*sc2.pb = 43;

	DeepCopy dc( 1, pIntDeep   );
	DeepCopy dc2(dc);
	*dc2.pb = 44;

	cout << " *sc.pb " << *sc.pb << "   *sc2.pb " << *sc2.pb << endl;
	cout << " *dc.pb " << *dc.pb << "   *dc2.pb " << *dc2.pb << endl;
}

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