std::try_emplace() in Maps and Unordered Maps of C++17 Last Updated : 08 Jul, 2020 Comments Improve Suggest changes Like Article Like Report In this article, we are going to learn try_emplace method in Maps and Unordered Maps. This method was added in C++17 (i.e gcc 9.1) version. This new function proposed behaves similarly to emplace(), but has an advantage that is, it will not construct the object associated with the key, if the key already exists. This will boost the performance in case objects of that type are expensive to create. Header File: #include <utility> Syntax: map_name.try_emplace(key, element); Parameters: The function accepts two mandatory parameters which are described below: key: It specifies the key to be inserted in the multimap container. element: It specifies the element to the key which is to be inserted in the map container. Return Value: The function does not return anything. Below is the program to illustrate try_emplace() in C++: CPP // C++ program for the illustration of // map::try_emplace() function in map #include <bits/stdc++.h> using namespace std; // Driver Code int main() { // Initializing a container map<string, string> m; // Inserting elements in random order m.try_emplace("a", "123"); m.try_emplace("b", "456"); m.try_emplace("a", "Won't be inserted"); m.try_emplace("c", "789"); m.try_emplace("c", "Won't be inserted"); // Print the elements cout << "\nThe map is : \n"; cout << "KEY\tELEMENT\n"; for (auto p : m) { cout << p.first << "\t" << p.second << endl; } return 0; } Output: Comment More infoAdvertise with us Next Article std::try_emplace() in Maps and Unordered Maps of C++17 C chirags_30 Follow Improve Article Tags : C++ Programs Data Structures DSA Practice Tags : Data Structures Similar Reads How to Create a Stack of Unordered_Map in C++? In C++, the stack is a container that follows the LIFO(Last In First Out) rule where new elements are added from one end (top) and removed from that end only. An unordered_map is an associative container that stores elements formed by a combination of key-value pairs, where the key should be unique. 2 min read Different Ways to Initialize an unordered_map in C++ Initialization is the process of assigning the initial values to the std::unordered_map elements. In this article, we will learn different methods to initialize the std::unordered_map in C++.Table of ContentUsing Initializer ListBy Inserting Elements One by OneFrom Another std::unordered_mapFrom Ano 3 min read How to Implement Custom Hash Functions for User-Defined Types in std::unordered_map? In C++ std::unordered_map is a data structure that implements a hash table and allows fast access to each element based on its key. However, when we want to use user-defined types as keys, we need to provide a custom hash function. In this article, we will learn how to implement a custom hash functi 3 min read How to Find the Union of Two Maps in C++? In C++, maps are associative containers that store key-value pairs. The union of two maps means combining their elements while ensuring that duplicate keys are handled appropriately. In this article, we will learn how to find the union of two maps in C++. For Example, Input: mapA = {{'a', 1}, {'b', 2 min read How to Add Elements to a Map in C++? In C++, a map is an associative container that stores the elements as key-value pairs where each element has a key and a mapped value. In this article, we will learn how to add elements to a map in C++ STL. For Example, Input: myMap = {{1, "Ram"}, {2, "Mohit"}}; Output: myMap = {{1, "Ram"}, {2, "Moh 2 min read Like