can someone give me an idea on how to deep copy..
this is my solution but i dont know am i right.. can someone correct it pleae....
Code:IPlist::IPlist (const IPlist & other) //copy constructor to create a deep copy of other IPlist object { nodeType *tmp = new nodeType; tmp->link = NULL; while(other != NULL) { tmp->lnk = other->link; tmp = other; other = other->link; } }
I recommend you use a stl container instead of a linked list.
Have you copy constructor call an the assignment operator. Ensure that the assignment operator does not permit a copy of an object to itself. Do the 'deep' copy within the assignment operator.
Your example requires a copy constructor and assignment operator for both IPList and NoseList.
The opposite is probably better. Have the copy assignment operator call the copy constructor, possibly with a custom swap member function.Have you copy constructor call an the assignment operator.
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
If you're considering using the constructor from within the assignment operator then you must read this: http://www.gotw.ca/gotw/023.htm
Actually, since you mentioned swap, you're actually suggesting that his copy-constructor should be a move-constructor, which is also a problem.
If the intention is to copy the entire list, how could it posibly work when new is only called for one node?
Try again writing this and put 'new' in the loop. Do it all on paper as you go because that will probably help a lot.
The code posted also cannot compile for a number of reasons, like using -> with a reference.
Last edited by iMalc; 10-20-2006 at 12:51 AM.
you mean put another node in the loop? or move tmp into the loop?
>> http://www.gotw.ca/gotw/023.htm
The example used in that link is not what laserlight had in mind. Instead, the idea is to copy construct a temporary inside the copy assignment operator, then swap the temporary with the local object (again inside the assignment operator). I believe this technique is actually recommended by Sutter in C++ Coding Standards, and it does not use a move constructor.
Last edited by Daved; 10-20-2006 at 08:50 AM.
this is an example from that website that Daved gave. is this useful for what i need???
Code:[Example: struct C { int i; void f(); const C& operator=( const C& ); }; const C& C::operator=( const C& other) { if ( this != &other ) { this->~C(); // lifetime of '*this' ends new (this) C(other); // new object of type C created f(); // well-defined } return *this; } C c1; C c2; c1 = c2; // well-defined c1.f(); // well-defined; c1 refers to // a new object of type C --end example]
Actually, that's the link iMalc gave. And no, it is not what you want to do at all. That is an example of what not to do, and the link says to "never write" code like that.
You can use the do_copy() example in that link. Or, as laserlight suggested, you can use a swap method to assist in implementing the copy assignment operator. For an example of that, see the answer to "2. What is the canonical form of strongly exception-safe copy assignment?" in: http://www.gotw.ca/gotw/059.htm
