unordered_multimap emplace() function in C++ STL (original) (raw)

Last Updated : 8 Aug, 2018

The unordered_multimap::emplace() is a built-in function in C++ STL which inserts a new {key, element} in the unordered_multimap container. The insertion is done automatically at the position according to the container's criterion. It increases the size of the container by one. Syntax:

unordered_multimap_name.emplace(key, element)

Parameters: The function accepts a single mandatory parameter key and element which is to be inserted in the container. Return Value: It returns an iterator which points to the newly inserted element. Below programs illustrates the above function: Program 1:

CPP `

// C++ program to illustrate // unordered_multimap::emplace() #include #include #include using namespace std;

int main() {

// declaration
unordered_multimap<int, int> sample;

// inserts key and elements
sample.emplace(1, 2);
sample.emplace(1, 2);
sample.emplace(1, 3);
sample.emplace(4, 9);
sample.emplace(60, 89);

cout << "Key and Elements: \n";
for (auto it = sample.begin(); it != sample.end(); it++)
    cout << "{" << it->first << ":" << it->second << "}\n ";

return 0;

}

`

Output:

Key and Elements: {60:89} {4:9} {1:3} {1:2} {1:2}

Program 2:

CPP `

// unordered_multimap::emplace #include #include #include using namespace std;

int main() {

// declaration
unordered_multimap<string, string> sample;

// inserts key and elements
sample.emplace("gopal", "dave");
sample.emplace("gopal", "dave");
sample.emplace("Geeks", "C++");
sample.emplace("multimap", "functions");
sample.emplace("multimap", "functions");

cout << "Key and Elements: \n";
for (auto it = sample.begin(); it != sample.end(); it++)
    cout << "{" << it->first << ":" << it->second << "}\n ";

return 0;

}

`

Output:

Key and Elements: {multimap:functions} {multimap:functions} {Geeks:C++} {gopal:dave} {gopal:dave}