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C++ List

In C++, a list is a sequence container that allows non-contiguous memory allocation. Lists are part of the Standard Template Library (STL) and provide a way to store elements in a doubly linked list format, allowing for efficient insertion and deletion of elements.

Key Topics

Overview of Lists

Lists provide several advantages:

  • Efficient insertions and deletions from both ends.
  • Elements can be added or removed without reallocating the entire list.
  • Supports bidirectional iteration.

Declaring Lists

To declare a list, include the list header and use the following syntax:

#include 
list myList;

Common List Operations

Here are some common operations you can perform on lists:

  • push_back(): Adds an element to the end of the list.
  • push_front(): Adds an element to the front of the list.
  • pop_back(): Removes the last element from the list.
  • pop_front(): Removes the first element from the list.
  • size(): Returns the number of elements in the list.
  • clear(): Removes all elements from the list.

Example: Basic List Operations

#include 
#include 
using namespace std;

int main() {
    list myList;
    myList.push_back(10);
    myList.push_front(20);
    myList.push_back(30);
    cout << "List size: " << myList.size() << endl;
    myList.pop_front();
    cout << "List size after pop_front: " << myList.size() << endl;
    myList.clear();
    cout << "List size after clear: " << myList.size() << endl;
    return 0;
}

Output:

List size: 3 List size after pop_front: 2 List size after clear: 0

Iterating Over Lists

You can iterate over the elements of a list using an iterator or a range-based for loop.

Example: Iterating with a Range-Based For Loop

#include 
#include 
using namespace std;

int main() {
    list myList = {10, 20, 30, 40, 50};
    cout << "List elements: ";
    for (int num : myList) {
        cout << num << " ";
    }
    return 0;
}

Output:

List elements: 10 20 30 40 50

Example: Iterating with Iterators

#include 
#include 
using namespace std;

int main() {
    list myList = {10, 20, 30, 40, 50};
    cout << "List elements using iterators: ";
    for (auto it = myList.begin(); it != myList.end(); ++it) {
        cout << *it << " ";
    }
    return 0;
}

Output:

List elements using iterators: 10 20 30 40 50

Exercises with Lists

Here are some exercises to practice your understanding of lists:

  • Create a list of strings and store names. Print each name using a range-based for loop.
  • Write a program that reads integers from the user and stores them in a list until the user enters -1. Then, print the sum of the entered integers.
  • Implement a function that takes a list and returns the maximum element.

Key Takeaways

  • Lists are sequence containers that allow efficient insertions and deletions.
  • Lists are implemented as doubly linked lists, providing bidirectional iteration.
  • Common operations include adding, removing, and accessing elements, as well as checking the size of the list.
  • Practice exercises can help solidify your understanding of how to use lists effectively in C++.
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