list front() function in C++ STL
Last Updated :
29 May, 2023
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.
Example
The below program illustrates the list::front() function.
C++
#include <bits/stdc++.h>
using namespace std;
int main()
{
list< int > demoList;
demoList.push_back(10);
demoList.push_back(20);
demoList.push_back(30);
demoList.push_back(40);
int ele = demoList.front();
cout << ele;
return 0;
}
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Time complexity: O(1)
Auxiliary Space: O(n) where n is the size of the list
Note: This function works in constant time complexity.
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