deep copy pointer of a struct object in c++

Question

I have a structure of the following type:

struct SPacket
{
    unsigned char payload[260]; 
    unsigned int payloadLength; 
};

I have a pointer object to this structure:

SPacket* ptrObj;

how can I perform a deep copy of ptrObj into a another object:

SPacket obj;

Possible duplicate of [pointers - duplicate object instance](http://stackoverflow.com/questions/14050058/pointers-duplicate-object-instance) — Khalil Khalaf, Aug 11 '16 at 13:56

score 8 · Accepted Answer · answered Aug 11 '16 at 13:52

8

The compiler-generated copy constructor will deep-copy the array member, so just use it:

SPacket obj(*ptrObj);

answered Aug 11 '16 at 13:52

Armen Tsirunyan

1

+1 but probably important to note, this is only correct for fixed size array's not allocated on the heap. – user1810087 Aug 11 '16 at 14:16
Error, no match for operator * – jaycode Aug 31 '17 at 17:46
@jaycode: If you're receiving that error, you probably don't have a pointer :) – Armen Tsirunyan Sep 01 '17 at 09:31
I can confirm. When the ptrObj is a reference (internally just a pointer) then there should be no asterisk. – Mark Jeronimus Aug 02 '19 at 17:03

bolov · Answer 2 · 2016-08-11T16:36:56.307

3

The solution is extremely simple: use the copy constructor:

SPacket obj = *ptrObj;

This will call the (implicit) copy constructor.

edited Aug 11 '16 at 16:36

answered Aug 11 '16 at 13:51

bolov

1

Thus would work in C too, no (after adding a `struct`)? – juanchopanza Aug 11 '16 at 13:52
@juanchopanza I guess yes, it would. What I meant by the intro, is that the copy constructor should be the first thought – bolov Aug 11 '16 at 13:53
But the solution is also extremely simple in C. – juanchopanza Aug 11 '16 at 14:21
@juanchopanza in this case, yes, it's the same. But if you have pointers inside the type you would need a copy/clone function. – bolov Aug 11 '16 at 16:32
Then you would have to implement a copy constructor in C++ anyway. – juanchopanza Aug 11 '16 at 16:36
@juanchopanza OK you win :p – bolov Aug 11 '16 at 16:37
Error, no match for operator * – jaycode Aug 31 '17 at 17:38

2 Answers2