The C++ std copy template is implemented this way: template Iterator2 copy (Iter

Question

The C++ std copy template is implemented this way: template Iterator2 copy (Iterator1 start, Iterator1 stop, Iterator2 result) { while (start ! = stop) { *"result = *start: ++start: ++result: } return result: } Suppose that we want to use copy this way: Container c1: Container c2: copy (c1.begin), c1.end(), c2.begin()): Which of the following conditions is required if the copy is to work properly? Iterator1 must have a copy constructor container must provide both const and non-const iterators c2 must already contain at least as many elements as c1 Element must have an assignment operator Element must have a copy constructor

Explanation / Answer

Ans) c2 must already contain at least as many elements as c1.

c2 must already contain at least as many elements as c1. Otherwise there will be few elements copied from c1 to c2 but programatically we will not see any error.

Test program where i verified the same is as follows. myvector(destination) when i changed it from 7 elements(same as myints) to less size than myints(source) it does no throw an error rather copied a few elements.

// copy algorithm example
#include <iostream>     // std::cout
#include <algorithm>    // std::copy
#include <vector>       // std::vector

int main () {
int myints[]={10,20,30,40,50,60,70};
std::vector<int> myvector (1);

std::copy ( myints, myints+7, myvector.begin() );

std::cout << "myvector contains:";
for (std::vector<int>::iterator it = myvector.begin(); it!=myvector.end(); ++it)
    std::cout << ' ' << *it;

std::cout << ' ';

return 0;
}

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