list front() function in C++ STL

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:

Note: This function works in constant time complexity.

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