C++ emplace_back

This function is used to insert new element at the end of the vector and increases the size of the vector container.

Syntax

Consider a vector 'v'. Syntax would be :

v.emplace_back(args);

Parameter

args : Arguments forwarded to construct the new element.

Return value

It does not return any value.

Example 1

Let's see a simple example.

#include <iostream>
#include<vector>
using namespace std;
int main()
{
vector<char> v{'C','+'};
v.emplace_back('+');
for(int i=0;i<v.size();i++)
cout<<v[i];
return 0;
}

Output:

In this example, size of the vector 'v' increases by adding new character value at the end of the vector using emplace_back function.

emplace vs insert

insert function is used to copy the objects into the vector while emplace function is used to construct them inside the vector only thus it avoids unnecessary operations to be performed.

Example 2

Let's see another simple example.

#include <iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> v{1,2,3,4,5};
v.emplace_back(6);
for(int i=0;i<v.size();i++)
cout<<v[i]<<" ";
return 0;
}

Output:

1 2 3 4 5 6

In this example, emplace_back function is used to add new integer value at the end of the vector i.e after the last element.