C++ Copy an array created with new

Question

I have created two arrays List1 and List2 with new in C++. List1 is updated with data. I would like to copy List1 to List2. I tried using

std::copy(std::begin(List1), std::end(List1), std::begin(List2));

However, this does not work and gives the following error message:

error: ‘begin’ is not a member of ‘std’

Any possible suggestions for this error? Or alternative ways to copy in C++?

@KerrekSB : Instead of new? I would not like to change this to std::vector, as the code is already under distribution. — SKPS
– SKPS, Commented Oct 8, 2013 at 16:41
std::begin is in <iterator>. They don't work on pointers, though. — Qaz
– Qaz, Commented Oct 8, 2013 at 16:42
Don't use begin and end then, just give it the first and one beyond the last members. std::copy(&List1[0], &List1[whatever_size_you_newed], List2); — doctorlove
– doctorlove, Commented Oct 8, 2013 at 16:51

P0W · Accepted Answer · 2013-10-08 16:45:36Z

2

"I have created two arrays List1 and List2 with new in C++"

The begin and end free functions won't work on a pointer.

Even if everything is correct, you may end up with no matching call to begin(T *&)

T is the type of your pointer.

Use std::vector or std::list other STL container or just simply static arrays to work with std::begin and std::end

answered Oct 8, 2013 at 16:45

P0W

48.1k9 gold badges79 silver badges124 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

khajvah Over a year ago

Is there an explanation? or they just didn't include its support

SKPS Over a year ago

@POW: Would you recommend using memcpy?

P0W Over a year ago

@khajvah See this, probably it answers your question

doctorlove Over a year ago

@SathishKrishnan that's why I asked what the arrays were. That will go wrong if the constructors need to do work

Mikael Persson Over a year ago

@khajvah The explanation is simply that a pointer is a pointer, not an array. A pointer can point to the start of an array (e.g., allocated with new[]), but there is no portable way to tell if it does, or how big that array is. This means that implementing end() is essentially impossible, and it would seem pointless to provide begin() without end().

|

Duncan Smith · Accepted Answer · 2013-10-08 16:43:34Z

0

Put this line towards the top of your cpp file:

#include <iterator>

answered Oct 8, 2013 at 16:43

Duncan Smith

5382 silver badges10 bronze badges

Comments

Neil Kirk · Accepted Answer · 2013-10-08 16:43:35Z

0

To use std::begin and std::end you need to include <iterator> and make sure your compiler supports C++11. However this won't fix your problem, as you cannot use them with pointers. Use std::vector instead.

answered Oct 8, 2013 at 16:43

Neil Kirk

22k9 gold badges57 silver badges97 bronze badges

Collectives™ on Stack Overflow

C++ Copy an array created with new

3 Answers 3

7 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

7 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related