📅 最后修改于: 2020-10-17 05:06:24 🧑 作者: Mango
C++ STL algorithm.rotate_copy()函数用于对范围为[first，last)的元素进行旋转复制。
template
OutputIterator rotate_copy (ForwardIterator first, ForwardIterator middle,
ForwardIterator last, OutputIterator result);
first：前向迭代器，指向要旋转范围内第一个元素的位置。
middle：正向迭代器，寻址到[first，last)范围内的元素，该元素将移至该范围内的第一个位置。
last：一个正向迭代器，它在元素要反转的范围内指向最后一个元素之后的位置。
结果：一个输出迭代器，指向目标范围中第一个元素的位置。
rotation_copy()函数将输出迭代器的地址返回到复制范围的末尾。
复杂度在[first，last)范围内是线性的：为每个元素执行一个赋值。
访问范围为[first，last)的对象。
结果和返回值之间的范围内的对象被更改。
如果元素分配或迭代器上的操作抛出异常，则此函数将引发异常。
注意：无效的参数会导致未定义的行为。
让我们看一下旋转给定字符串的简单示例：
#include
#include
#include
#include
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;
}
输出：
Before Rotate : N I K I T A
After Rotate : I K I T A N
让我们看另一个简单的例子：
#include
#include
#include
using namespace std;
int main()
{
vector src = {1, 2, 3, 4, 5};
auto pivot = find(src.begin(), src.end(), 3);
vector dest(src.size());
rotate_copy(src.begin(), pivot, src.end(), dest.begin());
for (const auto &i : dest) {
cout << i << ' ';
}
cout << '\n';
return 0;
}
输出：
3 4 5 1 2
让我们看另一个简单的例子：
#include
#include
#include
#include
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;
}
输出：
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
让我们看另一个简单的例子：
#include
#include
#include
#include
#include
using namespace std ;
int main()
{
const int VECTOR_SIZE = 8 ;
// Define a template class vector of strings
typedef vector 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;
}
输出：
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