Multisets are a type of associative containers similar to set, with an exception that multiple elements can have same values.
Some Basic Functions associated with multiset:
begin() – Returns an iterator to the first element in the multiset
end() – Returns an iterator to the theoretical element that follows last element in the multiset
size() – Returns the number of elements in the multiset
max_size() – Returns the maximum number of elements that the multiset can hold
empty() – Returns whether the multiset is empty
#include <iostream> #include <set> #include <iterator> using namespace std; int main() { // empty multiset container multiset <int, greater <int> > gquiz1; // insert elements in random order gquiz1.insert(40); gquiz1.insert(30); gquiz1.insert(60); gquiz1.insert(20); gquiz1.insert(50); gquiz1.insert(50); // 50 will be added again to the multiset unlike set gquiz1.insert(10); // printing multiset gquiz1 multiset <int, greater <int> > :: iterator itr; cout << "
The multiset gquiz1 is : "; for (itr = gquiz1.begin(); itr != gquiz1.end(); ++itr) { cout << ' ' << *itr; } cout << endl; // assigning the elements from gquiz1 to gquiz2 multiset <int> gquiz2(gquiz1.begin(), gquiz1.end()); // print all elements of the multiset gquiz2 cout << "
The multiset gquiz2 after assign from gquiz1 is : "; for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { cout << ' ' << *itr; } cout << endl; // remove all elements up to element with value 30 in gquiz2 cout << "
gquiz2 after removal of elements less than 30 : "; gquiz2.erase(gquiz2.begin(), gquiz2.find(30)); for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { cout << ' ' << *itr; } // remove all elements with value 50 in gquiz2 int num; num = gquiz2.erase(50); cout << "
gquiz2.erase(50) : "; cout << num << " removed " ; for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { cout << ' ' << *itr; } cout << endl; //lower bound and upper bound for multiset gquiz1 cout << "gquiz1.lower_bound(40) : " << *gquiz1.lower_bound(40) << endl; cout << "gquiz1.upper_bound(40) : " << *gquiz1.upper_bound(40) << endl; //lower bound and upper bound for multiset gquiz2 cout << "gquiz2.lower_bound(40) : " << *gquiz2.lower_bound(40) << endl; cout << "gquiz2.upper_bound(40) : " << *gquiz2.upper_bound(40) << endl; return 0; } |
The output of the above program is :
The multiset gquiz1 is : 60 50 50 40 30 20 10 The multiset gquiz2 after assign from gquiz1 is : 10 20 30 40 50 50 60 gquiz2 after removal of elements less than 30 : 30 40 50 50 60 gquiz2.erase(50) : 2 removed 30 40 60 gquiz1.lower_bound(40) : 40 gquiz1.upper_bound(40) : 30 gquiz2.lower_bound(40) : 40 gquiz2.upper_bound(40) : 60
List of functions of Multiset:
- begin() – Returns an iterator to the first element in the multiset.
- end() – Returns an iterator to the theoretical element that follows last element in the multiset.
- size() – Returns the number of elements in the multiset.
- max_size()– Returns the maximum number of elements that the multiset can hold.
- empty() – Returns whether the multiset is empty.
- pair insert(const g) – Adds a new element ‘g’ to the multiset.
- iterator insert (iterator position,const g) – Adds a new element ‘g’ at the position pointed by iterator.
- erase(iterator position)– Removes the element at the position pointed by the iterator.
- erase(const g)– Removes the value ‘g’ from the multiset.
- clear()– Removes all the elements from the multiset.
- key_comp() / value_comp()– Returns the object that determines how the elements in the multiset are ordered (‘<' by default).
- find(const g)– Returns an iterator to the element ‘g’ in the multiset if found, else returns the iterator to end.
- count(const g)– Returns the number of matches to element ‘g’ in the multiset.
- lower_bound(const g)– Returns an iterator to the first element that is equivalent to ‘g’ or definitely will not go before the element ‘g’ in the multiset.
- upper_bound(const g)– Returns an iterator to the first element that is equivalent to ‘g’ or definitely will go after the element ‘g’ in the multiset.
- multiset::swap()– This function is used to exchange the contents of two multisets but the sets must be of same type, although sizes may differ.
- multiset::operator=– This operator is used to assign new contents to the container by replacing the existing contents.
- multiset::emplace()– This function is used to insert a new element into the multiset container.
- multiset equal_range()– Returns an iterator of pairs. The pair refers to the range that includes all the elements in the container which have a key equivalent to k.
- multiset::emplace_hint() – Inserts a new element in the multiset.
- multiset::rbegin()– Returns a reverse iterator pointing to the last element in the multiset container.
- multiset::rend()– Returns a reverse iterator pointing to the theoretical element right before the first element in the multiset container.
- multiset::cbegin()– Returns a constant iterator pointing to the first element in the container.
- multiset::cend()– Returns a constant iterator pointing to the position past the last element in the container.
- multiset::crbegin()– Returns a constant reverse iterator pointing to the last element in the container.
- multiset::crend()– Returns a constant reverse iterator pointing to the position just before the first element in the container.
- multiset::get_allocator()– Returns a copy of the allocator object associated with the multiset.
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