C++ multiset - insert() Function
The C++ multiset::insert function is used to insert new elements in the container. This results into increasing the multiset size by the number of elements inserted.
Syntax
//single element version iterator insert (const value_type& val); //single element with hint version iterator insert (iterator position, const value_type& val); //range version template <class InputIterator> void insert (InputIterator first, InputIterator last);
//single element version iterator insert (const value_type& val); iterator insert (value_type&& val); //single element with hint version iterator insert (const_iterator position, const value_type& val); iterator insert (const_iterator position, value_type&& val); //range version template <class InputIterator> void insert (InputIterator first, InputIterator last); //initializer list version void insert (initializer_list<value_type> il);
Parameters
position |
Specify the hint for the position where the element can be inserted. |
val |
Specify the value to be copied (or moved) to the inserted elements. |
first |
Specify the starting position of InputIterator. Copies of the elements in the range [first,last) are inserted in the container. |
last |
Specify the last position of InputIterator. Copies of the elements in the range [first,last) are inserted in the container. |
il |
Specify the initializer_list object. |
Return Value
Returns an iterator pointing to the newly inserted element in the multiset.
Time Complexity
- Logarithmic i.e, Θ(log(n)) if a single element is inserted, but constant i.e, Θ(1) if position provided is optimal.
- Multiple elements insertion: Average case - linear in number of elements inserted. Worst case - Linearithmic: number of elements inserted multiplied by log of (container size + number of elements inserted).
Example:
In the example below, the multiset::insert function is used to insert elements in the given multiset.
#include <iostream>
#include <set>
using namespace std;
int main (){
multiset<int> MSet1 = {10, 20, 30};
multiset<int> MSet2 = {10, 20, 30};
multiset<int>::iterator it;
//single element version
MSet1.insert(55);
//single element with hint version
it = MSet2.begin();
MSet2.insert(++it, 15);
cout<<"MSet1 contains: ";
for(it = MSet1.begin(); it != MSet1.end(); ++it)
cout<<*it<<" ";
cout<<"\nMSet2 contains: ";
for(it = MSet2.begin(); it != MSet2.end(); ++it)
cout<<*it<<" ";
return 0;
}
The output of the above code will be:
MSet1 contains: 10 20 30 55 MSet2 contains: 10 15 20 30
Example:
A range of elements can also be inserted into a multiset. Consider the example below.
#include <iostream>
#include <set>
#include <vector>
using namespace std;
int main (){
multiset<int> MSet = {10, 20, 30};
vector<int> MyVec = {15, 30, 45, 60, 75};
multiset<int>::iterator multiset_it;
vector<int>::iterator vec_it;
//range version - insert a range of
//elements of MyVec into MSet
vec_it = MyVec.begin();
MSet.insert(vec_it, vec_it + 3);
cout<<"MSet contains: ";
for(multiset_it = MSet.begin(); multiset_it != MSet.end(); ++multiset_it)
cout<<*multiset_it<<" ";
return 0;
}
The output of the above code will be:
MSet contains: 10 15 20 30 30 45
Example:
Similarly, the initializer list version can be used to insert elements in the given multiset.
#include <iostream>
#include <set>
using namespace std;
int main (){
multiset<int> MSet = {10, 15};
multiset<int>::iterator it;
//initializer list version
initializer_list<int> ilist = {11, 12, 13, 14};
MSet.insert(ilist);
cout<<"MSet contains: ";
for(it = MSet.begin(); it != MSet.end(); ++it)
cout<<*it<<" ";
return 0;
}
The output of the above code will be:
MSet contains: 10 11 12 13 14 15
❮ C++ <set> Library
