C++/STL Algorithms Modifying sequence operations/copy backward
Use std::copy_backward to place elements in one vector into another vector in reverse order
#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <vector>
#include <iterator>
int main()
{
int a1[ 5 ] = { 1, 3, 5, 7, 9 };
int a2[ 5 ] = { 2, 4, 5, 7, 9 };
std::vector< int > v1( a1, a1 + 5 );
std::vector< int > v2( a2, a2 + 5 );
std::ostream_iterator< int > output( cout, " " );
std::copy( v1.begin(), v1.end(), output ); // display vector output
std::copy( v2.begin(), v2.end(), output ); // display vector output
std::vector< int > results( v1.size() );
// place elements of v1 into results in reverse order
std::copy_backward( v1.begin(), v1.end(), results.end() );
cout << "\n\nAfter copy_backward, results contains: ";
std::copy( results.begin(), results.end(), output );
cout << endl;
return 0;
}
/*
1 3 5 7 9 2 4 5 7 9
After copy_backward, results contains: 1 3 5 7 9
*/
Use the copy_backward algorithms: Shift it right by 2 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_backward(vector1.begin(), vector1.end() - 2, vector1.end());
vector<char>::iterator pos;
for (pos=vector1.begin(); pos!=vector1.end(); ++pos) {
cout << *pos << " ";
}
return 0;
}
/*
a b a b c d e f g h i h k l m n o p q r s t u v w x
*/