C++ Tutorial/STL Algorithms Modifying sequence operations/iter swap
Swap first and second value with iter_swap
<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. */
- include <iostream>
- include <list>
- include <algorithm>
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;
} int main() {
list<int> coll; // insert elements from 1 to 9 for (int i=1; i<=9; ++i) { coll.push_back(i); } PRINT_ELEMENTS(coll); // swap first and second value iter_swap (coll.begin(), ++coll.begin()); PRINT_ELEMENTS(coll); // swap first and last value iter_swap (coll.begin(), --coll.end()); PRINT_ELEMENTS(coll);
}</source>
1 2 3 4 5 6 7 8 9 2 1 3 4 5 6 7 8 9 9 1 3 4 5 6 7 8 2
Use iterators to swap elements at locations 0 and 1 of an array
<source lang="cpp">#include <iostream> using std::cout; using std::endl;
- include <algorithm>
- 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::iter_swap( &a[ 0 ], &a[ 1 ] ); // swap with iterators cout << "\nArray a after swapping a[0] and a[1] using iter_swap:\n "; std::copy( a, a + 10, output ); cout << endl; return 0;
}</source>
Array a contains: 1 2 3 4 5 6 7 8 9 10 Array a after swapping a[0] and a[1] using iter_swap: 2 1 3 4 5 6 7 8 9 10