C++ Forward_list Library - emplace_front() Function

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Description

The C++ function std::forward_list::emplace_front() constructs and inserts new element at the beginning of the forward_list and increases size of list by one.

Declaration

Following is the declaration for std::forward_list::emplace_front() function form std::forward_list header.

C++11

template <class... Args>
void emplace_front (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::forward_list::emplace_front() function.

#include <iostream>
#include <forward_list>

using namespace std;

int main(void) {

   forward_list<int> fl = {2, 3, 4, 5};

   fl.emplace_front(1);

   cout << "List contains following elements" << endl;

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

   return 0;
}

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

List contains following elements
1
2
3
4
5