list size() function in C++ STL

The list::size() is a built-in function in C++ STL that is used to find the number of elements present in a list container. That is, it is used to find the size of the list container.
Syntax:

list_name.size();

Time Complexity - Linear O(1) as per c++11 standard. Possible because the implementation maintains the size field.

Parameters: This function does not accept any parameter.
Return Value: This function returns the number of elements present in the list container list_name. Below program illustrate the list::size() function in C++ STL:

CPP

// CPP program to illustrate the
// list::size() 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);

    // getting size of the list
    int size = demoList.size();

    cout << "The list contains " << size << " elements";

    return 0;
}

list size() function in C++ STL

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