C++ Vector Library - emplace_back() Function

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Description

The C++ function std::vector::emplace_back() inserts new element at the end of vector. Reallocation happens if there is need of more space.

This method increases container size by one.

Declaration

Following is the declaration for std::vector::emplace_back() function form std::vector header.

C++11

template <class... Args>
void emplace_back (Args&&... args);

Parameters

args − Arguments forwarded to construct the new element.

Return value

None

Exceptions

If reallocation fails bad_alloc exception is thrown.

Time complexity

Constant i.e. O(1)

Example

The following example shows the usage of std::vector::emplace_back() function.

#include <iostream>
#include <vector>
using namespace std;

int main(void) {
   vector<int> v = {1, 2, 3};

   v.emplace_back(4);
   v.emplace_back(5);

   for (auto it = v.begin(); it != v.end(); ++it)
      cout << *it << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

1
2
3
4
5