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× C++ Standard Library C++ STL Library


The C++ forward_list::emplace_after function is used to insert new element at specified position in a forward_list. Each insertion of element increases the forward_list container size by one.

Syntax

template <class... Args>
iterator emplace_after (const_iterator position, Args&&... args);

Parameters

position Specify the position in the forward_list where the new element need to be inserted.
args Arguments forwarded to construct the new element.

Return Value

An iterator that points to the newly emplaced element.

Time Complexity

Constant i.e, Θ(1).

Example:

In the below example, the forward_list::emplace_after function is used to insert new element at specified position in a forward_list f_list.

#include <iostream>
#include <forward_list>
using namespace std;
 
int main (){
  forward_list<int> f_list{10, 20, 30, 40, 50};
  forward_list<int>::iterator it;

  //insert a new element at position = 3
  it = f_list.begin();
  advance(it, 2);
  f_list.emplace_after(it, 100);

  //insert a new element at position = 4
  f_list.emplace_after(it, 200);

  cout<<"f_list contains: ";
  cout<<"f_list contains: ";
  for(it = f_list.begin(); it != f_list.end(); it++)
   cout<<*it<<" ";   

  return 0;
}

The output of the above code will be:

f_list contains: 10 20 30 200 100 40 50 

Example:

Lets see another example where the forward_list called f_list contains string values.

#include <iostream>
#include <forward_list>
using namespace std;
 
int main (){
  forward_list<string> f_list;
  forward_list<string>::iterator it;

  it = f_list.before_begin();
  //insert new element in the forward_list
  f_list.emplace_after(it, "JAN");
  f_list.emplace_after(it, "FEB");
  f_list.emplace_after(it, "MAR");
  f_list.emplace_after(it, "APR");
  f_list.emplace_after(it, "MAY");
  f_list.emplace_after(it, "JUN");

  cout<<"f_list contains: ";
  for(it = f_list.begin(); it != f_list.end(); it++)
  {
   cout<<*it<<" ";   
  }
  return 0;
}

The output of the above code will be:

f_list contains: JUN MAY APR MAR FEB JAN 

❮ C++ <forward_list> Library