Copies the elements in the range, defined by[first, last), to another range beginning atd_first (copy destination range).

[edit]Parameters

[edit]Return value

Output iterator to the element in the destination range, one past the last element copied.

[edit]Complexity

Given\(\scriptsize N\)N asstd::distance(first, last):

For the overloads with anExecutionPolicy, there may be a performance cost ifForwardIt1's value type is notMoveConstructible.

[edit]Exceptions

The overloads with a template parameter namedExecutionPolicy report errors as follows:

• If execution of a function invoked as part of the algorithm throws an exception andExecutionPolicy is one of thestandard policies,std::terminate is called. For any otherExecutionPolicy, the behavior is implementation-defined.
• If the algorithm fails to allocate memory,std::bad_alloc is thrown.

[edit]Possible implementation

template<class InputIt,class OutputIt>OutputIt copy(InputIt first, InputIt last,              OutputIt d_first){for(; first!= last;(void)++first,(void)++d_first)*d_first=*first; return d_first;}

template<class InputIt,class OutputIt,class UnaryPred>OutputIt copy_if(InputIt first, InputIt last,                 OutputIt d_first, UnaryPred pred){for(; first!= last;++first)if(pred(*first)){*d_first=*first;++d_first;} return d_first;}

[edit]Notes

In practice, implementations ofstd::copy avoid multiple assignments and use bulk copy functions such asstd::memmove if the value type isTriviallyCopyable and the iterator types satisfyLegacyContiguousIterator.

When copying overlapping ranges,std::copy is appropriate when copying to the left (beginning of the destination range is outside the source range) whilestd::copy_backward is appropriate when copying to the right (end of the destination range is outside the source range).

[edit]Example

#include <algorithm>#include <iostream>#include <iterator>#include <numeric>#include <vector> int main(){std::vector<int> from_vector(10);std::iota(from_vector.begin(), from_vector.end(),0);std::vector<int> to_vector;    std::copy(from_vector.begin(), from_vector.end(),std::back_inserter(to_vector)); // or, alternatively,//  std::vector<int> to_vector(from_vector.size());//  std::copy(from_vector.begin(), from_vector.end(), to_vector.begin());// either way is equivalent to//  std::vector<int> to_vector = from_vector; std::cout<<"to_vector contains: ";    std::copy(to_vector.begin(), to_vector.end(),std::ostream_iterator<int>(std::cout," "));std::cout<<'\n'; std::cout<<"odd numbers in to_vector are: ";    std::copy_if(to_vector.begin(), to_vector.end(),std::ostream_iterator<int>(std::cout," "),[](int x){return x%2!=0;});std::cout<<'\n'; std::cout<<"to_vector contains these multiples of 3: ";    to_vector.clear();    std::copy_if(from_vector.begin(), from_vector.end(),std::back_inserter(to_vector),[](int x){return x%3==0;}); for(constint x: to_vector)std::cout<< x<<' ';std::cout<<'\n';}

to_vector contains: 0 1 2 3 4 5 6 7 8 9odd numbers in to_vector are: 1 3 5 7 9to_vector contains these multiples of 3: 0 3 6 9

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]See also

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