C++ Tutorial/STL Algorithms Non modifying sequence operations/copy

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Copy all letters three elements behind the "f"

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;
    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << " ";
    }
    std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}
int main()
{
    /* initialize source collection with ""..........abcdef..........""
     */
    vector<char> source(10,".");
    for (int c="a"; c<="f"; c++) {
        source.push_back(c);
    }
    source.insert(source.end(),10,".");
    PRINT_ELEMENTS(source,"source: ");
    // copy all letters three elements in front of the "a"
    vector<char> c1(source.begin(),source.end());
    copy (c1.begin()+10, c1.begin()+16,  // source range
          c1.begin()+7);                 // destination range
    PRINT_ELEMENTS(c1,"c1:     ");
    // copy all letters three elements behind the "f"
    vector<char> c2(source.begin(),source.end());
    copy_backward (c2.begin()+10, c2.begin()+16,  // source range
                   c2.begin()+19);                // destination range
    PRINT_ELEMENTS(c2,"c2:     ");
}
source: . . . . . . . . . . a b c d e f . . . . . . . . . .
c1:     . . . . . . . a b c d e f d e f . . . . . . . . . .
c2:     . . . . . . . . . . a b c a b c d e f . . . . . . .

Copy and insert list

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <vector>
#include <list>
#include <deque>
#include <set>
#include <algorithm>
using namespace std;
int main()
{
    list<int> coll1;
    // insert elements from 1 to 9 into the first collection
    for (int i=1; i<=9; ++i) {
        coll1.push_back(i);
    }
    // copy the elements of coll1 into coll2 by appending them
    vector<int> coll2;
    copy (coll1.begin(), coll1.end(),      // source
          back_inserter(coll2));           // destination
    // copy the elements of coll1 into coll3 by inserting them at the front
    // - reverses the order of the elements
    deque<int> coll3;
    copy (coll1.begin(), coll1.end(),      // source
          front_inserter(coll3));          // destination
    // copy elements of coll1 into coll4
    // - only inserter that works for associative collections
    set<int> coll4;
    copy (coll1.begin(), coll1.end(),      // source
          inserter(coll4,coll4.begin()));  // destination
}

Copy istream_iterator to ostream_iterator

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <algorithm>
#include <iterator>
#include <string>
using namespace std;
int main()
{
    copy (istream_iterator<string>(cin),         // beginning of source
          istream_iterator<string>(),            // end of source
          ostream_iterator<string>(cout,"\n"));  // destination
}
a
a
Terminate batch job (Y/N)? n

Copy vector and list

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <vector>
#include <list>
#include <deque>
#include <algorithm>
using namespace std;
int main()
{
    list<int>   coll1;
    vector<int> coll2;
    
    // insert elements from 1 to 9
    for (int i=1; i<=9; ++i) {
        coll1.push_back(i);
    }
    // resize destination to have enough room for the overwriting algorithm
    coll2.resize (coll1.size());
    /* copy elements from first into second collection
     * - overwrites existing elements in destination
     */
    copy (coll1.begin(), coll1.end(),     // source
          coll2.begin());                 // destination
    /* create third collection with enough room
     * - initial size is passed as parameter
     */
    deque<int> coll3(coll1.size());
    // copy elements from first into third collection
    copy (coll1.begin(), coll1.end(),     // source
          coll3.begin());                 // destination
}

Display all elements in a vector

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <iterator>
using namespace std;
int main()
{
    // create empty vector for strings
    vector<string> sentence;
    // reserve memory for five elements to avoid reallocation
    sentence.reserve(5);
    // append some elements
    sentence.push_back("Hello,");
    sentence.push_back("how");
    sentence.push_back("are");
    sentence.push_back("you");
    sentence.push_back("?");
    // print elements separated with spaces
    copy (sentence.begin(), sentence.end(),
          ostream_iterator<string>(cout," "));
    cout << endl;
}
Hello, how are you ?

Print all elements in a list with copy function

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <list>
#include <algorithm>
#include <iterator>
using namespace std;
void printLists (const list<int>& l1, const list<int>& l2)
{
    cout << "list1: ";
    copy (l1.begin(), l1.end(), ostream_iterator<int>(cout," "));
    cout << endl << "list2: ";
    copy (l2.begin(), l2.end(), ostream_iterator<int>(cout," "));
    cout << endl << endl;
}
int main()
{
    // create two empty lists
    list<int> list1, list2;
    // fill both lists with elements
    for (int i=0; i<6; ++i) {
        list1.push_back(i);
        list2.push_front(i);
    }
    printLists(list1, list2);
}
list1: 0 1 2 3 4 5
list2: 5 4 3 2 1 0

Use copy function to print all elements in a deque

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <iostream>
#include <deque>
#include <string>
#include <algorithm>
#include <iterator>
using namespace std;
int main()
{
    // create empty deque of strings
    deque<string> coll;
    // insert several elements
    coll.assign (3, string("string"));
    coll.push_back ("last string");
    coll.push_front ("first string");
    // print elements separated by newlines
    copy (coll.begin(), coll.end(),
          ostream_iterator<string>(cout,"\n"));
    cout << endl;
}
first string
string
string
string
last string

Use copy to copy elements in one container to another container

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */

#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;
    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << " ";
    }
    std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}
int main()
{
    vector<int> coll1;
    list<int> coll2;
    INSERT_ELEMENTS(coll1,1,9);
    /* copy elements of coll1 into coll2
     * - use back inserter to insert instead of overwrite
     */
    copy (coll1.begin(), coll1.end(),         // source range
          back_inserter(coll2));              // destination range
    /* print elements of coll2
     * - copy elements to cout using an ostream iterator
     */
    copy (coll2.begin(), coll2.end(),         // source range
          ostream_iterator<int>(cout," "));   // destination range
    cout << endl;
}
1 2 3 4 5 6 7 8 9

Use copy to copy elements of one container into another container in reverse order

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */

#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;
    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << " ";
    }
    std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}
int main()
{
    vector<int> coll1;
    list<int> coll2;
    INSERT_ELEMENTS(coll1,1,9);
    /* copy elements of coll1 into coll2
     * - use back inserter to insert instead of overwrite
     */
    copy (coll1.begin(), coll1.end(),         // source range
          back_inserter(coll2));              // destination range
    /* copy elements of coll1 into coll2 in reverse order
     * - now overwriting
     */
    copy (coll1.rbegin(), coll1.rend(),       // source range
          coll2.begin());                     // destination range
    // print elements of coll2 again
    copy (coll2.begin(), coll2.end(),         // source range
          ostream_iterator<int>(cout," "));   // destination range
    cout << endl;
}
9 8 7 6 5 4 3 2 1

Use copy() to copy value from one vector to vector

#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
void print(int elem)
{
  cout << elem << " ";
}
int main(int argc, char** argv)
{
  vector<int> vectOne, vectTwo;
  vectOne.push_back(1);
  vectOne.push_back(2);
  vectOne.push_back(3);
  vectOne.push_back(4);
  vectTwo.resize(vectOne.size());
  copy(vectOne.begin(), vectOne.end(), vectTwo.begin());
  for_each(vectTwo.begin(), vectTwo.end(), &print);
  return (0);
}

Use copy to copy value from vector to a list

#include <algorithm>
#include <vector>
#include <list>
#include <iostream>
using namespace std;
int main (){
    list <int> l;
    for (int nCount = 0; nCount < 10; ++ nCount)
        l.push_back (nCount);
    list <int>::const_iterator li;
    for ( li = l.begin (); li != l.end (); ++ li )
        cout << *li << " ";
    vector <int> v (l.size () * 2);
    vector <int>::iterator iLastPos;
    iLastPos = copy ( l.begin (), l.end (), v.begin () );
    vector <int>::const_iterator vi;
    for ( vi = v.begin (); vi != v.end (); ++ vi )
        cout << *vi << " ";
    return 0;
}

Use copy to output all elements in a container

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */

#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;
    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << " ";
    }
    std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}
int main()
{
    vector<int> coll1;
    list<int> coll2;
    INSERT_ELEMENTS(coll1,1,9);
    /* copy elements of coll1 into coll2
     * - use back inserter to insert instead of overwrite
     */
    copy (coll1.begin(), coll1.end(),         // source range
          back_inserter(coll2));              // destination range
    /* print elements of coll2
     * - copy elements to cout using an ostream iterator
     */
    copy (coll2.begin(), coll2.end(),         // source range
          ostream_iterator<int>(cout," "));   // destination range
    cout << endl;
}
1 2 3 4 5 6 7 8 9

Use std::copy to print all elements in a set

#include <iostream>
using std::cout;
using std::endl;
#include <set>
#include <algorithm>
#include <iterator> // ostream_iterator
int main()
{
   double a[ 5 ] = { 2.1, 4.2, 9.5, 2.1, 3.7 };
   std::set< double, std::less< double > > doubleSet( a, a + 5 );;
   std::ostream_iterator< double > output( cout, " " );
   cout << "doubleSet contains: ";
   std::copy( doubleSet.begin(), doubleSet.end(), output );
   cout << endl;
   return 0;
}
doubleSet contains: 2.1 3.7 4.2 9.5

Use the copy algorithms: Shift the contents of vector1 left by 4 positions

#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
using namespace std;
int main()
{
  string s("abcdefghihklmnopqrstuvwxyz");
  vector<char> vector1(s.begin(), s.end());
  copy(vector1.begin() + 4, vector1.end(), vector1.begin());
  vector<char>::iterator pos;
  for (pos=vector1.begin(); pos!=vector1.end(); ++pos) {
        cout << *pos << " ";
  }

  return 0;
}
e f g h i h k l m n o p q r s t u v w x y z w x y z

Use the generic copy to duplicate vectors

#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
using namespace std;
int main()
{
  string s("abcdefghihklmnopqrstuvwxyz");
  vector<char> vector1(s.begin(), s.end());
  vector<char> vector2(vector1.size());
  // Copy vector1 to vector2:
  copy(vector1.begin(), vector1.end(), vector2.begin());
  assert (vector1 == vector2);
  vector<char>::iterator pos;
  for (pos=vector1.begin(); pos!=vector1.end(); ++pos) {
        cout << *pos << " ";
  }
  cout << "\n\n\n\n";
  for (pos=vector2.begin(); pos!=vector2.end(); ++pos) {
        cout << *pos << " ";
  }
  return 0;
}
a b c d e f g h i h k l m n o p q r s t u v w x y z

a b c d e f g h i h k l m n o p q r s t u v w x y z