multimap::erase() in C++ STL Last Updated : 18 Nov, 2020 Comments Improve Suggest changes Like Article Like Report multimap::erase() is a built-in function in C++ STL which is used to erase element from the container. It can be used to erase keys, elements at any specified position or a given range. Syntax for erasing a key: multimap_name.erase(key) Parameters: The function accepts one mandatory parameter key which specifies the key to be erased in the multimap container. Return Value: The function does not return anything. It erases all the elements with the specified key. CPP // C++ program to illustrate // multimap::erase(key) #include <bits/stdc++.h> using namespace std; int main() { // initialize container multimap<int, int> mp; // insert elements in random order mp.insert({ 2, 30 }); mp.insert({ 1, 40 }); mp.insert({ 3, 60 }); mp.insert({ 2, 20 }); mp.insert({ 5, 50 }); // prints the elements cout << "The multimap before using erase() is : \n"; cout << "KEY\tELEMENT\n"; for (auto itr = mp.begin(); itr != mp.end(); ++itr) { cout << itr->first << '\t' << itr->second << '\n'; } // function to erase given keys mp.erase(1); mp.erase(2); // prints the elements cout << "\nThe multimap after applying erase() is : \n"; cout << "KEY\tELEMENT\n"; for (auto itr = mp.crbegin(); itr != mp.crend(); ++itr) { cout << itr->first << '\t' << itr->second << '\n'; } return 0; } Output: The multimap before using erase() is : KEY ELEMENT 1 40 2 30 2 20 3 60 5 50 The multimap after applying erase() is : KEY ELEMENT 5 50 3 60 Syntax for removing a position: multimap_name.erase(iterator position) Parameters: The function accept one mandatory parameter position which specifies the iterator that is the reference to the position of the element to be erased. Return Value: The function does not returns anything. Program below illustrate the above syntax: CPP // C++ program to illustrate // multimap::erase(position) #include <bits/stdc++.h> using namespace std; int main() { // initialize container multimap<int, int> mp; // insert elements in random order mp.insert({ 2, 30 }); mp.insert({ 1, 40 }); mp.insert({ 3, 60 }); mp.insert({ 2, 20 }); mp.insert({ 5, 50 }); // prints the elements cout << "The multimap before using erase() is : \n"; cout << "KEY\tELEMENT\n"; for (auto itr = mp.begin(); itr != mp.end(); ++itr) { cout << itr->first << '\t' << itr->second << '\n'; } // function to erase given position auto it = mp.find(2); mp.erase(it); auto it1 = mp.find(5); mp.erase(it1); // prints the elements cout << "\nThe multimap after applying erase() is : \n"; cout << "KEY\tELEMENT\n"; for (auto itr = mp.crbegin(); itr != mp.crend(); ++itr) { cout << itr->first << '\t' << itr->second << '\n'; } return 0; } Output: The multimap before using erase() is : KEY ELEMENT 1 40 2 30 2 20 3 60 5 50 The multimap after applying erase() is : KEY ELEMENT 3 60 2 20 1 40 Syntax for erasing a given range: multimap_name.erase(iterator position1, iterator position2) Parameters: The function accepts two mandatory parameters which are described below: position1 - specifies the iterator that is the reference to the element from which removal is to be done. position2 - specifies the iterator that is the reference to the element upto which removal is to be done. Return Value: The function does not returns anything. It removes all the elements in the given range of iterators. Program below illustrate the above syntax: CPP // C++ program to illustrate // multimap::erase() #include <bits/stdc++.h> using namespace std; int main() { // initialize container multimap<int, int> mp; // insert elements in random order mp.insert({ 2, 30 }); mp.insert({ 1, 40 }); mp.insert({ 3, 60 }); mp.insert({ 2, 20 }); mp.insert({ 5, 50 }); // prints the elements cout << "The multimap before using erase() is : \n"; cout << "KEY\tELEMENT\n"; for (auto itr = mp.begin(); itr != mp.end(); ++itr) { cout << itr->first << '\t' << itr->second << '\n'; } // function to erase in a given range // find() returns the iterator reference to // the position where the element is auto it1 = mp.find(2); auto it2 = mp.find(5); mp.erase(it1, it2); // prints the elements cout << "\nThe multimap after applying erase() is : \n"; cout << "KEY\tELEMENT\n"; for (auto itr = mp.crbegin(); itr != mp.crend(); ++itr) { cout << itr->first << '\t' << itr->second << '\n'; } return 0; } Output: The multimap before using erase() is : KEY ELEMENT 1 40 2 30 2 20 3 60 5 50 The multimap after applying erase() is : KEY ELEMENT 5 50 1 40 Comment More infoAdvertise with us Next Article multimap clear() function in C++ STL gopaldave Follow Improve Article Tags : Misc C++ STL CPP-Functions cpp-multimap +1 More Practice Tags : CPPMiscSTL Similar Reads Multimap in C++ STL In C++, multimap is an associative container similar to map, but it can have multiple elements with same keys. It stores all the elements in increasing order based on their keys by default but can be changed if required. It provides fast insertion, deletion and search on this sorted data.Example:CPP 8 min read Commonly Used Methodsmultimap::begin() and multimap::end() in C++ STLmultimap::begin() is a built-in function in C++ STL that returns an iterator referring to the first element in the multimap container. Since the multimap container contains the element in an ordered way, begin() will point to that element that will come first according to the container's sorting cri 3 min read multimap size() function in C++ STLThe multimap::size() is a built-in function in C++ STL which returns the number of elements in the multimap container. Syntax: multimap_name.size() Parameters: The function does not accept any parameter. Return Value: This function returns the number of elements a multimap container has. CPP // C++ 1 min read multimap empty() function in C++ STLThe multimap::empty() is a boolean type observer function in C++ STL which tells whether the container is empty or not. This function returns true when the multimap container is empty (i.e. the size of the container is 0). Being an observer function it does not modify the multimap in any way. Syntax 1 min read multimap insert() in C++ STLThe multimap::insert is a built-in function in C++ STL that is used to insert elements in the multimap container. Syntax: iterator multimap_name.insert({key, element}) Parameters: The function accepts a pair that consists of a key and element which is to be inserted into the multimap container. Retu 2 min read multimap::emplace() in C++ STLThe multimap::emplace() is a built-in function in C++ STL which inserts the key and its element in the multimap container. It effectively increases the container size by one as multimap is the container that stores multiple keys with same values. Syntax: multimap_name.emplace(key, element) Parameter 1 min read multimap find() in C++ STLmultimap::find() is a built-in function in C++ STL which returns an iterator or a constant iterator that refers to the position where the key is present in the multimap. In case of multiple same keys being present, the iterator that refers to one of the keys (typically the first one). In case we wis 2 min read multimap::count() in C++ STLThe multimap::count is a built-in function in C++ STL which returns the number of times a key is present in the multimap container. Syntax: multimap_name.count(key) Parameters: The function accepts one mandatory parameter key which specifies the key whose count in multimap container is to be returne 1 min read multimap::erase() in C++ STLmultimap::erase() is a built-in function in C++ STL which is used to erase element from the container. It can be used to erase keys, elements at any specified position or a given range. Syntax for erasing a key: multimap_name.erase(key) Parameters: The function accepts one mandatory parameter key wh 4 min read multimap clear() function in C++ STLThe multimap clear() function is an inbuilt function in C++ STL which is used to remove all elements from the multimap container (which are destroyed), leaving the container with a size of 0. Syntax : mymultimap_name.clear() Parameters: This function does not take any arguments. Return Value: This f 2 min read multimap::swap() in C++ STLmultimap::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 Other Member Methodsmultimap maxsize() in C++ STLThe multimap::max_size() is a built-in function in C++ STL which returns the maximum number of elements a multimap container can hold. 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Internally, a multimap is implemented as a red-black tree. Each element of a multimap is treated as a pair. The first value is referred to as key and the second value is referred to 6 min read Difference between pair in Multiset and Multimap in C++ STL Pairs in C++: The pair container is a simple container defined in <utility> header consisting of two data elements or objects. The first element is referenced as ‘first’ and the second element as ‘second’ and the order is fixed (first, second). Pair is used to combine together two values which 5 min read Multimap vs Map in C++ STL with Examples Map in C++ STL Map stores unique key-value pairs in a sorted manner. Each key is uniquely associated with a value that may or may not be unique. A key can be inserted or deleted from a map but cannot be modified. Values assigned to keys can be changed. It is a great way for quickly accessing value u 8 min read Common Multimap ProblemsDescending Order in Map and Multimap of C++ STLWe have discussed map in C++ STL and multimap in C++ STL. The default behavior of these data structures is to store elements in ascending order. How to store elements in reverse order or descending order when inserting in map and multimap? We can use the third parameter, that is std::greater along w 3 min read How to traverse through all values for a given key in multimap?Given a multimap and a key of the multimap, our task is to simply display the (key - value) pairs of the given key. In multimap we can have multiple (key - value) pair for the same key. Suppose our multimap contains key value1 102 202 302 403 504 604 70key : 2key value2 202 302 40Like in unordered_m 5 min read Like