std::swap is used for swapping of elements between two containers. One of its variation is
std::swap_ranges, which as the name suggests is used for swapping the elements within a range. It simply exchanges the values of each of the elements in the range [first1, last1) with those of their respective elements in the range beginning at first2. If we look at its internal working, we will find that this function itself uses std::swap(). Syntax:
std::swap_ranges (ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2); Here, first1, last1 and first2 are forward iterators. Returns: It returns an iterator to the last element swapped in the second sequence.
CPP // C++ program to demonstrate // the use of std::swap_ranges #include <iostream> #include <algorithm> #include <vector> using namespace std; int main() { // Declaring first vector vector<int> v1; int i; // v1 contains 0 1 2 3 4 5 6 7 8 9 for (i = 0; i < 10; ++i) { v1.push_back(i); } // Declaring second vector // v2 contains 100 100 100 100 100 vector<int> v2(5, 100); // Performing swap std::swap_ranges(v1.begin() + 3, v1.begin() + 7, v2.begin()); // Displaying v1 after swapping for (i = 0; i < 10; ++i) { cout << v1[i] << " "; } cout << "\n"; // Displaying v2 after swapping for (i = 0; i < 5; ++i) { cout << v2[i] << " "; } return 0; } Output:
0 1 2 100 100 100 100 7 8 9 3 4 5 6 100
Here, in this program we have swapped elements from v1 starting at v1.begin()+3 till v1.begin()+7, with the values starting from v2.begin(), so in place of swapping the whole vector, we have performed swapping in a range.
Where can it be used ? It can be used when we have to find whether a given container contains the same element in its first half as well as in the second half as well, i.e.,
whether both the halves are identical to each other or not. CPP // C++ program to demonstrate // the use of std::swap_ranges #include <iostream> #include <algorithm> #include <vector> using namespace std; int main() { // Here 5 is the central element and the two halves // on its either side contain the same elements 1 2 3 4 vector<int> v1 = { 1, 2, 3, 4, 5, 1, 2, 3, 4 }; int i; // Declaring second vector and making it equal to v1 vector<int> v2 = v1; // Here there is no central element and the two halves // are 1 2 3 4 and 1 2 3 5 which are different vector<int> v3 = { 1, 2, 3, 4, 1, 2, 3, 5 }; // Declaring fourth vector and making it equal to v3 vector<int> v4 = v3; // Performing swap between two halves of vector v1 if (v1.size() % 2 == 0) std::swap_ranges(v1.begin(), v1.begin() + (v1.size() / 2), v1.begin() + v1.size() / 2); else std::swap_ranges(v1.begin(), v1.begin() + v1.size() / 2, v1.begin() + (v1.size() / 2) + 1); if (v1 == v2) { cout << "Yes"; } else { cout << "No"; } // Now, Performing swap between two halves of vector v3 if (v3.size() % 2 == 0) std::swap_ranges(v3.begin(), v3.begin() + (v3.size() / 2), v3.begin() + v3.size() / 2); else std::swap_ranges(v3.begin(), v3.begin() + v3.size() / 2, v3.begin() + (v3.size() / 2) + 1); cout << "\n"; if (v3 == v4) { cout << "Yes"; } else { cout << "No"; } return 0; } Output:
Yes No
Explanation of code: Here, in this code, we have declared a vector and then assigned it to another vector, and then in the first vector, we are swapping values in the first half with the second half depending upon whether it contains odd no. of elements or not. If after swapping the values, the new first vector is same as second vector (old first vector), this means that both the halves are same. So, in the first vector 1 2 3 4 5 1 2 3 4, it contains same element in both the halves, so Yes is printed, whereas in second vector 1 2 3 4 1 2 3 5, second half contains one different element than first half, i.e., 4 in place of 5, so No is printed.
Time Complexity: It is linear in the distance between first and last.
Similar Reads
std::iter_swap in C++
std::swap is used for swapping of elements between two containers. One of the other way of doing this same thing is facilitated by std::iter_swap, which as the name suggests is used for swapping the elements with the help of an iterator. It simply exchanges the values of the elements pointed to by t
3 min read
set::swap() in C++ STL
Sets are a type of associative containers in which each element has to be unique, because the value of the element identifies it. The value of the element cannot be modified once it is added to the set, though it is possible to remove and add the modified value of that element. set::swap() This func
2 min read
list::swap() in C++ STL
Lists are containers used in C++ to store data in a non contiguous fashion, Normally, Arrays and Vectors are contiguous in nature, therefore the insertion and deletion operations are costlier as compared to the insertion and deletion option in Lists. list::swap()This function is used to swap the con
2 min read
stack swap() in C++ STL
Stacks are a type of container adaptors with LIFO(Last In First Out) type of work, where a new element is added at one end and (top) an element is removed from that end only. stack::swap()This function is used to swap the contents of one stack with another stack of same type but the size may vary. S
2 min read
queue::swap() in C++ STL
Queue is also an abstract data type or a linear data structure, which follows a particular order in which the operations are performed. The order is First In First Out (FIFO). In a FIFO data structure, the first element added to the queue will be the first one to be removed. queue::swap() swap() fun
2 min read
multimap::swap() in C++ STL
multimap::swap() is used to swap the contents of one multimap with another multimap of same type and size. Syntax:- multimap1.swap(multimap2) Parameters : The name of the multimap with which the contents have to be swapped. Result : All the elements of the 2 multimap are swapped. Examples: Input: mu
2 min read
std::prev in C++
std::prev returns an iterator pointing to the element after being advanced by certain number of positions in the reverse direction. It is defined inside the header file iterator. It returns a copy of the argument advanced by the specified amount in the backward direction. If it is a random-access it
5 min read
std::next in C++
std::next returns an iterator pointing to the element after being advanced by certain no. of positions. It is defined inside the header file . It does not modify its arguments and returns a copy of the argument advanced by the specified amount. If it is a random-access iterator, the function uses ju
4 min read
rotate() in C++ STL
In C++, rotate() is a built-in function used to rotate the elements of a range in left or right direction such that the element pointed to by a specified iterator becomes the new first element of the range. Let's take a look at an example: [GFGTABS] C++ #include <bits/stdc++.h> using namespace
4 min read
is_sorted() in C++ STL
In C++, is_sorted() is a built-in function used to check whether the element of the given range is sorted or not in ascending order. In this article, we will learn about is_sorted() function in C++. Let’s take a quick look at a simple example that illustrates is_sorted() method: [GFGTABS] C++ #inclu
4 min read