list push_front() function in C++ STL

The list::push_front() is a built-in function in C++ STL which is used to insert an element at the front of a list container just before the current top element. This function also increases the size of the container by 1.

Syntax

list_name.push_front(dataType value)

• Parameters: value- The element to be inserted at the front of the list.
• Return Value: This function does not return any value.

Example: The following program demonstrates the use of list::push_front():

#include <iostream>
#include <list>
using namespace std;

int main()
{
    // Creating a list
    list<int> demoList;

    // Adding elements using push_back()
    demoList.push_back(10);
    demoList.push_back(20);
    demoList.push_back(30);
    demoList.push_back(40);

    // Printing initial list
    cout << "Initial List: ";
    for (int val : demoList)
        cout << val << " ";

    // Inserting element at the front
    demoList.push_front(5);

    // Printing updated list
    cout << "\n\nList after push_front(): ";
    for (int val : demoList)
        cout << val << " ";

    return 0;
}

Initial List: 10 20 30 40 

List after push_front(): 5 10 20 30 40 

Explanation:

• initially, elements 10, 20, 30, 40 are inserted at the end using push_back().
• push_front(5) call inserts 5 at the beginning.
• std::list is a doubly linked list, no shifting of elements occurs.
• new element becomes the first node of the list.