The C++ algorithm rotate_copy method is employed to generate a rotated duplicate of the elements within the specified range [first, last).
In this process, the sequence will initiate from the middle element of the original sequence, with the last element being succeeded by the first.
Moreover, it concatenates the element located between the first and the middle with the elements positioned between the middle and the last element.
Syntax
template <class ForwardIterator, class OutputIterator>
OutputIterator rotate_copy (ForwardIterator first, ForwardIterator middle,
ForwardIterator last, OutputIterator result);
Parameter
A forward iterator indicating the location of the initial element within the range to undergo rotation.
A middle iterator points to the element in the range [first, last) that is shifted to the beginning of the range.
The last parameter is a forward iterator indicating the position immediately after the last element in the range that is being reversed.
An output iterator pointing to the location of the initial element within the target range.
Return value
The rotate_copy function provides an output iterator pointing to the end of the duplicated range.
Complexity
The complexity increases linearly within the specified range [first, last) and involves executing an assignment for every element in that range.
Data races
The elements within the range [first, last) are being accessed.
The items within the range from the outcome to the value that is sent back are altered.
Exceptions
This function will raise an exception if either an assignment to an element or an operation on an iterator results in an exception.
Note: The invalid parameters cause an undefined behavior.
Example 1
Let's explore a straightforward illustration of rotating a provided string:
#include <algorithm>
#include <iostream>
#include <string>
#include <iterator>
using namespace std;
int main() {
string str = " N I K I T A";
string result;
cout << "Before Rotate : "<< str << endl;
rotate_copy(str.begin(), str.begin() + 2, str.end(),
back_inserter(result));
cout <<"After Rotate : " << result << endl;
return 0;
}
Output:
Before Rotate : N I K I T A
After Rotate : I K I T A N
Example 2
Let's see another simple example:
#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
int main()
{
vector<int> src = {1, 2, 3, 4, 5};
auto pivot = find(src.begin(), src.end(), 3);
vector<int> dest(src.size());
rotate_copy(src.begin(), pivot, src.end(), dest.begin());
for (const auto &i : dest) {
cout << i << ' ';
}
cout << '\n';
return 0;
}
Output:
3 4 5 1 2
Example 3
Let's see another simple example:
#include <iostream>
#include <algorithm>
#include <vector>
#include <iomanip>
using namespace std;
void print(char a[], int N)
{
for(int i = 0; i < N; i++)
{
cout << (i + 1) << ". " << setw(1)
<< left << a[i] << " ";
}
cout << endl;
}
int main()
{
char s[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H'};
int slen = sizeof(s) / sizeof(char), tlen = slen;
char t[tlen];
cout << "Character array s[] : ";
print(s, slen);
cout << "Rotate s[] with \'C\' as middle element and copy in t[]" << endl;
rotate_copy(s, s + 2, s + slen, t);
cout << "Character array t[] : ";
print(t, tlen);
cout << "Rotate t[] with \'A\' as middle element and copy in s[]" << endl;
rotate_copy(t, t + 6, t + tlen, s);
cout << "Character array s[] : ";
print(s, slen);
cout << "Character array t[] : ";
print(t, tlen);
return 0;
}
Output:
Character array s[] : 1. A 2. B 3. C 4. D 5. E 6. F 7. G 8. H
Rotate s[] with 'C' as middle element and copy in t[]
Character array t[] : 1. C 2. D 3. E 4. F 5. G 6. H 7. A 8. B
Rotate t[] with 'A' as middle element and copy in s[]
Character array s[] : 1. A 2. B 3. C 4. D 5. E 6. F 7. G 8. H
Character array t[] : 1. C 2. D 3. E 4. F 5. G 6. H 7. A 8. B
Example 4
Let's see another simple example:
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>
using namespace std ;
int main()
{
const int VECTOR_SIZE = 8 ;
// Define a template class vector of strings
typedef vector<string> StrVector ;
//Define an iterator for template class vector of strings
typedef StrVector::iterator StrVectorIt ;
StrVector Tongue_Twister(VECTOR_SIZE) ;
StrVector Rotated_Twister(VECTOR_SIZE) ;
StrVectorIt start, middle, end, it, RTstart, RTend ;
start = Tongue_Twister.begin() ; // location of first
// element of Tongue_Twister
end = Tongue_Twister.end() ; // one past the location last
// element of Tongue_Twister
middle = start + 3 ; // start position for
// rotating elements
RTstart = Rotated_Twister.begin() ; // location of first
// element of Rotated_Twister
RTend = Rotated_Twister.end() ; // one past the location last
// element of Rotated_Twister
//Initialize vector Tongue_Twister
Tongue_Twister[0] = "she" ;
Tongue_Twister[1] = "sells" ;
Tongue_Twister[2] = "sea" ;
Tongue_Twister[3] = "shells" ;
Tongue_Twister[4] = "by";
Tongue_Twister[5] = "the";
Tongue_Twister[6] = "sea" ;
Tongue_Twister[7] = "shore" ;
cout << "Before calling rotate_copy:\n" << endl ;
// print content of Tongue_Twister
cout << "Try this Tongue Twister: " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << "\n\n" ;
// rotate the items in the vector Tongue_Twist to the right by
// 3 positions and copy the results to Rotated_Twister
rotate_copy(start, middle, end, RTstart) ;
cout << "After calling rotate_copy:\n" << endl ;
// print content of Tongue_Twister
cout << "Tongue_Twister: " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << "\n\n" ;
// print content of Rotated_Twister
cout << "Now try the rotated Tongue Twister: " ;
for(it = RTstart; it != RTend; it++)
cout << *it << " " ;
cout << "\n\n" ;
return 0;
}
Output:
Before calling rotate_copy:
Try this Tongue Twister: she sells sea shells by the sea shore
After calling rotate_copy:
Tongue_Twister: she sells sea shells by the sea shore
Now try the rotated Tongue Twister: shells by the sea shore she sells sea
