Use the copy() in CPP

[Garett]

Hi, I am the student of the BscIT. I have to make the project on the C++ language. But I can not know anything about the copy() function of the C++ language. So, I would like to know about the copy() function in C++ language. I also would like to know how can I use the copy() function in the C++ program code. Thus, Can anyone help me to know about the copy() function.

[Modifier]

The following program demonstrates you about the copy() function in the C++ language :

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main ()
 {
  int mint[]={10,20,30,40,50,60,70};
  vector<int> mvctr;
  vector<int>::iterator t;
  mvctr.resize(7);  
  copy ( mint, mint+7, mvctr.begin() );
  cout << "mvctr contains:";
  for (t=mvctr.begin(); t!=mvctr.end(); ++t)
    cout << " " << *t;
  cout << endl;
  return 0;
}

Output:

myvector contains: 10 20 30 40 50 60 70

[Praetor]

PROGRAM :

#include <iostream>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
template <class S>
inline void PRINTELEMENTS (const S& cl, const char* optstr="")
{
    typename S::constiterator ps;
    std::cout << optstr;
    for (ps=cl.begin(); ps!=cl.end(); ++ps) 
{
        std::cout << *ps << ' ';
    }
    std::cout << std::endl;
}
template <class S>
inline void INSERTELEMENTS (S& cl, int fst, int lst)
{
    for (int j=fst; j<=lst; ++j)
 {
        cl.insert(cl.end(),j);
    }
}
int main()
{
    vector<int> cl1;
   list<int> cl2;
    INSERTELEMENTS(cl1,1,9);
    copy (cl1.begin(), cl1.end(),        
          backinserter(cl2));              
    copy (cl2.begin(), cl2.end(),      
          ostreamiterator<int>(cout," "));
    cout << endl;
}

OUTPUT :

1 2 3 4 5 6 7 8 9

[Katty]

The copy() function can be used to copy the elements in the given range [first,last) into a range that can be beginning at result. The behavior of this function template can be similar to :

template<class IptItrtr, class OutputIptItrtr>
  OutputIptItrtr copy ( InputIptItrtr first, InputIptItrtr last, 
OutputIptItrtr result )
{
  while (fst!=lst) *rslt++ = *fst++;
  return rslt;
}

[kelfro]

The program that can describes the copy() function in the C++ language :

#include <vector>
#include <algorithm>
#include <iostream>
int main() 
{
   using namespace std;
   vector <int> w1, w2;
   vector <int>::iterator Itr1, Itr2;
   int j;
   for ( j = 0 ; j <= 5 ; j++ )
      w1.pushback( 10 * j );
   int jj;
   for ( jj = 0 ; jj <= 10 ; jj++ )
      w2.pushback( 3 * jj );
   cout << "w1 = ( " ;
   for ( Itr1 = w1.begin( ) ; Itr1 != w1.end( ) ; Itr1++ )
      cout << *Itr1 << " ";
   cout << ")" << endl;
   cout << "w2 = ( " ;
   for ( Itr2 = w2.begin( ) ; Itr2 != w2.end( ) ; Itr2++ )
      cout << *Itr2 << " ";
   cout << ")" << endl;
   copy( w1.begin( ), w1.begin( ) + 3, w2.begin( ) + 4 );
   cout << "w2 with w1 insert = ( " ;
   for ( Itr2 = w2.begin( ) ; Itr2 != w2.end( ) ; Itr2++ )
      cout << *Itr2 << " ";
   cout << ")" << endl;
   copy( w2.begin( )+4, w2.begin( ) + 7, w2.begin( ) + 2 );
   cout << "w2 with shifted insert = ( " ;
   for ( Itr2 = w2.begin( ) ; Itr2 != w2.end( ) ; Itr2++ )
      cout << *Itr2 << " ";
   cout << ")" << endl;
}

Output :

w1 = ( 0 10 20 30 40 50 )
w2 = ( 0 3 6 9 12 15 18 21 24 27 30 )
w2 with w1 insert = ( 0 3 6 9 0 10 20 21 24 27 30 )
w2 with shifted insert = ( 0 3 0 10 20 10 20 21 24 27 30 )

[Zecho]

The following can be the parameters of the copy() function in the C++ language :
1. rslt : This parameter can be used for the output iterator that can be to the starting position in the sequence that can be the destination.
2. fst, lst : These parameters can be used for the input iterators to the final and starting positions in a sequence that can be copied.