List and Vector in C++
Difference between List and Vector in C++
In C++, both list and vector are container classes used to store and manipulate data. However, they have some fundamental differences that can affect their performance and suitability for different use cases. In this blog post, we will explore the differences between list and vector in C++, and when to use each one.
List
A list is a container class that stores data in a linked list structure. Each element in the list contains a value and a pointer to the next element in the list. Unlike an array, where elements are stored contiguously in memory, the elements in a list can be located anywhere in memory. It makes inserting or deleting elements in a list a relatively cheap operation, since only the pointers of the neighboring elements need to be updated.
To create a list in C++, you need to include the <list> header file and declare a list object. Here's an example:
#include <list>
std::list<int>my_list;
You can add elements to the list using the push_back() or push_front() methods:
my_list.push_back(1);
my_list.push_front(2);
You can access elements in the list using iterators. An iterator is an object that points to an element in the list. Here's an example of how to iterate through a list:
for (std::list<int>::iterator it = my_list.begin(); it != my_list.end(); ++it) {
std::cout<< *it << " ";
}
Vector
A vector is a container class that stores data in a dynamically allocated array. Like an array, the elements in a vector are stored contiguously in memory. It makes accessing elements in a vector a fast operation, since the position of an element can be calculated using a simple formula. However, inserting or deleting elements in a vector can be expensive, since it requires shifting all the elements that come after the insertion or deletion point.
To create a vector in C++, you need to include the <vector> header file and declare a vector object. Here's an example:
#include <vector>
std::vector<int>my_vector
You can add elements to the vector using the push_back() method:
my_vector.push_back(1);
my_vector.push_back(2);
You can access elements in the vector using the [] operator or iterators. Here's an example of how to iterate through a vector using iterators:
for (std::vector<int>::iterator it = my_vector.begin(); it != my_vector.end(); ++it) {
std::cout<< *it << " ";
}
Differences
The main difference between list and vector is the way they store elements in memory. List stores elements in a linked list structure, while vector stores elements in a dynamically allocated array. This difference affects the performance and behavior of each container class in different ways.
Insertion and Deletion
Inserting or deleting an element in a list is a relatively cheap operation, since it only requires updating the pointers of the neighboring elements. However, accessing a specific element in a list can be slow, since we need to traverse the list to find the element.
Memory Allocation
List does not require contiguous memory allocation because each element can be located anywhere in memory. It makes list suitable for storing elements of different sizes or types. However, list requires more memory overhead because each element needs to store a pointer to the next element in the list.
Size
List and vector have different behaviors when it comes to size. List does not have a size() method, since calculating the size of a linked list requires traversing the entire list. Instead, list has a empty() method, which returns true if the list is empty.
Vector has a size() method, which returns the number of elements in the vector. Vector also has an empty() method, which returns true if the vector is empty.
When to Use Each Container
Now that we know the differences between list and vector, let's discuss when to use each container.
Use list when:
- You need to insert or delete elements frequently
- You don't need to access elements randomly
- You need to store elements of different sizes or types
Use vector when:
- You need to access elements randomly
- You don't need to insert or delete elements frequently
- You need to store elements of the same size and type
Conclusion
List and vector are both container classes in C++, but they have fundamental differences in the way they store and manipulate data. List stores elements in a linked list structure, while vector stores elements in a dynamically allocated array. Each container has its own advantages and disadvantages, and choosing the right container that depends on the specific requirements of your application. By understanding the differences between list and vector, you can make an informed decision about which container to use in your code.