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list front() function in C++ STL

  • Difficulty Level : Easy
  • Last Updated : 20 Jun, 2018

The list::front() is a built-in function in C++ STL which is used to return a reference to the first element in a list container. Unlike the list::begin() function, this function returns a direct reference to the first element in the list container.

Syntax:

list_name.front() 

Parameters: This function does not accept any parameter, it simply returns a reference to the first element in the list container.

Return Value: This function returns a direct reference to the first element in the list container.

Exception: This function creates an undefined behavior when used with an empty list container.



Below program illustrates the list::front() function.




// CPP program to illustrate the
// list::front() function
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
    // Creating a list
    list<int> demoList;
  
    // Add elements to the List
    demoList.push_back(10);
    demoList.push_back(20);
    demoList.push_back(30);
    demoList.push_back(40);
  
    // get the first element using front()
    int ele = demoList.front();
  
    // Print the first element
    cout << ele;
  
    return 0;
}
Output:
10

Note: This function works in constant time complexity.

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