C++ Tutorial/STL Algorithms Modifying sequence operations/swap ranges

Illustrating the generic swap_ranges algorithm

<source lang="cpp">#include <iostream>

1. include <cassert>
2. include <algorithm>
3. include <vector>
4. include <string>

using namespace std;

int main() {

 string s("HELLO");
 string s2("THERE");
 vector<char> vector1(s.begin(), s.end());
 vector<char> vector2(s2.begin(), s2.end());
 // Swap the contents of vector1 and vector2:
 swap_ranges(vector1.begin(), vector1.end(), vector2.begin());

 for(int i=0;i<vector1.size();i++){
    cout << vector1[i] ;
 }
 cout << "\n\n\n\n\n";
 for(int i=0;i<vector2.size();i++){
    cout << vector2[i] ;
 }
 return 0;

}</source>

THERE


HELLO

Swap elements in first five elements of an array with elements in last five elements

<source lang="cpp">#include <iostream> using std::cout; using std::endl;

1. include <algorithm>
2. include <iterator>

int main() {

  int a[ 10 ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
  std::ostream_iterator< int > output( cout, " " );
  cout << "Array a contains:\n   ";
  std::copy( a, a + 10, output );
  std::swap_ranges( a, a + 5, a + 5 );
  std::copy( a, a + 10, output );
  cout << endl;
  return 0;

}</source>

Array a contains:
   1 2 3 4 5 6 7 8 9 10 6 7 8 9 10 1 2 3 4 5

Use swap_ranges to mirror first three with last three elements

<source lang="cpp">/* 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.
*/

1. include <iostream>
2. include <vector>
3. include <deque>
4. include <list>
5. include <set>
6. include <map>
7. include <string>
8. include <algorithm>
9. include <iterator>
10. include <functional>
11. include <numeric>

/* 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);
   }

} using namespace std; int main() {

   vector<int> coll1;
   deque<int> coll2;
   INSERT_ELEMENTS(coll1,1,9);
   INSERT_ELEMENTS(coll2,11,23);
   PRINT_ELEMENTS(coll1,"coll1: ");
   PRINT_ELEMENTS(coll2,"coll2: ");
   // mirror first three with last three elements in coll2
   swap_ranges (coll2.begin(), coll2.begin()+3,    // first range
                coll2.rbegin());                   // second range
   PRINT_ELEMENTS(coll2,"\ncoll2: ");

}</source>

coll1: 1 2 3 4 5 6 7 8 9
coll2: 11 12 13 14 15 16 17 18 19 20 21 22 23
coll2: 23 22 21 14 15 16 17 18 19 20 13 12 11

Use swap_ranges to swap elements in one container with corresponding elements in another container

<source lang="cpp">/* 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.
*/

1. include <iostream>
2. include <vector>
3. include <deque>
4. include <list>
5. include <set>
6. include <map>
7. include <string>
8. include <algorithm>
9. include <iterator>
10. include <functional>
11. include <numeric>

/* 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);
   }

} using namespace std; int main() {

   vector<int> coll1;
   deque<int> coll2;
   INSERT_ELEMENTS(coll1,1,9);
   INSERT_ELEMENTS(coll2,11,23);
   PRINT_ELEMENTS(coll1,"coll1: ");
   PRINT_ELEMENTS(coll2,"coll2: ");
   // swap elements of coll1 with corresponding elements of coll2
   deque<int>::iterator pos;
   pos = swap_ranges (coll1.begin(), coll1.end(),  // first range
                      coll2.begin());              // second range
   PRINT_ELEMENTS(coll1,"\ncoll1: ");
   PRINT_ELEMENTS(coll2,"coll2: ");
   if (pos != coll2.end()) {
       cout << "first element not modified: "
            << *pos << endl;
   }

}</source>

coll1: 1 2 3 4 5 6 7 8 9
coll2: 11 12 13 14 15 16 17 18 19 20 21 22 23
coll1: 11 12 13 14 15 16 17 18 19
coll2: 1 2 3 4 5 6 7 8 9 20 21 22 23
first element not modified: 20