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

Khalil Khalaf
– Khalil Khalaf

2016-08-11 13:56:21 +00:00
Commented Aug 11, 2016 at 13:56 — Khalil Khalaf
– Khalil Khalaf, Commented Aug 11, 2016 at 13:56

Armen Tsirunyan · Accepted Answer · 2016-08-11 13:52:04Z

8

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

SPacket obj(*ptrObj);

answered Aug 11, 2016 at 13:52

Armen Tsirunyan

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4 Comments

user1810087 Over a year ago

+1 but probably important to note, this is only correct for fixed size array's not allocated on the heap.

jaycode Over a year ago

Error, no match for operator *

Armen Tsirunyan Over a year ago

@jaycode: If you're receiving that error, you probably don't have a pointer :)

Mark Jeronimus Over a year ago

I can confirm. When the ptrObj is a reference (internally just a pointer) then there should be no asterisk.

bolov · Accepted Answer · 2016-08-11 16:36:56Z

3

The solution is extremely simple: use the copy constructor:

SPacket obj = *ptrObj;

This will call the (implicit) copy constructor.

edited Aug 11, 2016 at 16:36

answered Aug 11, 2016 at 13:51

bolov

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7 Comments

juanchopanza Over a year ago

Thus would work in C too, no (after adding a struct)?

bolov Over a year ago

@juanchopanza I guess yes, it would. What I meant by the intro, is that the copy constructor should be the first thought

juanchopanza Over a year ago

But the solution is also extremely simple in C.

bolov Over a year ago

@juanchopanza in this case, yes, it's the same. But if you have pointers inside the type you would need a copy/clone function.

juanchopanza Over a year ago

Then you would have to implement a copy constructor in C++ anyway.

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