C++/STL Algorithms Modifying sequence operations/iter swap — различия между версиями
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Версия 14:21, 25 мая 2010
Swap first and second value with iter_swap
/* 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);
}
/*
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
#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;
}
/*
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
*/