c++ - Cannot use the copy function -

what wrong copy (which generic function), here? cannot run code.

vector<int> a(10, 2); vector<int> b(a.size());  auto ret = copy(a.begin(), a.end(), b);  (auto : b) cout << << endl; 

here's output after compiling:

1>------ build started: project: project1, configuration: debug win32 ------ 1>  mainex.cpp 1>c:\program files (x86)\microsoft visual studio 11.0\vc\include\xutility(2176): error c4996: 'std::_copy_impl': function call parameters may unsafe - call relies on caller check passed values correct. disable warning, use -d_scl_secure_no_warnings. see documentation on how use visual c++ 'checked iterators' 1>          c:\program files (x86)\microsoft visual studio 11.0\vc\include\xutility(2157) : see declaration of 'std::_copy_impl' 1>          c:\users\amin\documents\visual studio 2012\projects\project1\project1\mainex.cpp(40) : see reference function template instantiation '_outit std::copy<std::_vector_iterator<_myvec>,std::vector<_ty>>(_init,_init,_outit)' being compiled 1>          1>          [ 1>              _outit=std::vector<int>, 1>              _myvec=std::_vector_val<std::_simple_types<int>>, 1>              _ty=int, 1>              _init=std::_vector_iterator<std::_vector_val<std::_simple_types<int>>> 1>          ] ========== build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== 

std::copy 3rd parameter iterator, pass b.begin() instead:

 #include <iterator>  ...   auto ret = std::copy(a.begin(), a.end(), b.begin()); 

the better way construct b a, in case, compiler knows allocate needed memory @ once , construct elements a:

 vector<int> b(a.begin(), a.end()); 

or

 std::vector<int> b = a;