Description : The list::size() is a built-in function in C++ STL which is used to find the number of elements present in a list container.
Example :
// Creating a list
std::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();
std::cout << "The list contains " << size << " elements";