C++ <forward_list> - front() Function

The C++ forward_list::front function returns a reference to the first element of the forward_list. Please note that, Unlike the forward_list::begin function, which returns the iterator pointing to the first element, it returns the a direct reference to the same element of the forward_list.

Syntax

• C++11

reference front();
const_reference front() const;

Parameters

No parameter is required.

Return Value

A reference to the first element of the forward_list.

Time Complexity

Constant i.e, Θ(1).

Example:

In the example below, the forward_list::front function is used to access the first element of the forward_list flist.

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

  cout<<"The first element of flist is: ";
  cout<<flist.front();

  cout<<"\n\nAdd 100 to the first element of the flist.\n";
  flist.front() = flist.front() + 100;

  cout<<"Now, The first element of flist is: ";
  cout<<flist.front();  
  return 0;
}

The output of the above code will be:

The first element of flist is: 10

Add 100 to the first element of the flist.
Now, The first element of flist is: 110