45 lines
1.7 KiB
Markdown
45 lines
1.7 KiB
Markdown
---
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title: C++ Lists
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---
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# What is a STL List?
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Lists in C++ are a powerful tool similar to its more well known cousin, C++ Vectors. While Vectors are a sequential container
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where elements are indexed in a continuous chain, Lists are also a sequential container but they are organized differently.
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List elements point to its next element so all elements are ordered in sequence but they don't use indexing.
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How? You may ask. They do this not by indexing but using a special tool called iterators. Iterators are like special pointers
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whose job is to maintain the order of the list elements kind of like the link between two train cars. Here is a nice visual
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of how Lists are organized compared to Vectors and Arrays.
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Traversal in a list is slow as compared to Vectors and Arrays, but once a position has been found, insertion and deletion are quick.
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## How to declare a List
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Possible declarations of a list:
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```c++
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#include <list>
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int main()
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{
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std::list<int> list1 = {1, 2, 3, 4};
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std::list<int> list2 (list1);
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std::list<int> list3 = list2;
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std::list<int> list4 {list3};
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std::list<int>* list5 = new std::list<int>(list4);
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}
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```
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## Functions used with List
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* size() : Returns the number of elements in the list
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* begin() : Returns an iterator pointing to the first element of the list
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* end() : Returns an iterator pointing to the theoretical last element which follows the last element
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* push_front(data) – Adds a new element with value 'data' at the beginning of the list
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* push_back(data) – Adds a new element with value 'data' at the end of the list
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* pop_front() – Removes the first element of the list
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* pop_back() – Removes the last element of the list
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## How to use these Functions
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Numbers.size();
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