added functions to be used in lists (#18541)

client/src/pages/guide/english/cplusplus/lists/index.md

@@ -12,8 +12,22 @@ whose job is to maintain the order of the list elements kind of like the link be
 of how Lists are organized compared to Vectors and Arrays. 
 ![img](https://imgur.com/SiU8uTe.png)
 
+Traversal in a list is slow as compared to Vectors and Arrays, but once a position has been found, insertion and deletion are quick.
 
 ## How to declare a List
 If you want to declare a List of Numbers you write:
 
 '''std::list<int> Numbers;''' 
+
+## Functions used with List
+size() : Returns the number of elements in the list
+begin() : Returns an iterator pointing to the first element of the list
+end() : Returns an iterator pointing to the theoretical last element which follows the last element
+push_front(data) – Adds a new element with value 'data' at the beginning of the list
+push_back(data) – Adds a new element with value 'data' at the end of the list
+pop_front() – Removes the first element of the list
+pop_back() – Removes the last element of the list
+
+## How to use these Functions
+
+Numbers.size();