1. Standard Template Library Model
CSCE 121
Slides adapted from J. Michael Moore
Based on slides created by Bjarne Stroustrup and Jennifer Welch

2. Basic STL Model iterators Algorithms sort, find, search, copy, …
Containers vector, list, map, unordered_map, …
Separation of concerns
Algorithms manipulate data, but don’t know about containers
Containers store data, but don’t know about algorithms
Algorithms and containers interact through iterators
Each container has its own iterator types
iterators

3. Iterators
A single iterator is essentially the position of an element
A pair of iterators defines a sequence
the beginning (points to first element, if any)
the end (points to the one-beyond-the-last element) …
begin:
end:

4. Iterators … begin: Supports the “iterator operations”:
end:
Supports the “iterator operations”:
Go to next element: ++
Get value: *
Check if two iterators point to same element: ==
Frequently a pointer type, but not necessarily
Some iterators support more operations (--, +, [ ] )

5. One-Past-The-Last
An iterator point to (refers to, denotes) an element of a sequence
The end of the sequence is “one past the last element”, not the last element!
Reason is to elegantly represent an empty sequence
One-past-the last element is not an element
you can compare an iterator pointing to it
but you cannot dereference it (get its value) 1 2 3
the end:
An empty sequence:
begin: end:
some iterator:

6. Containers
Hold sequences in different ways
vector 1 2 3

7. Containers
Hold sequences in different ways
list (doubly-linked) 1 2

8. Containers Hold sequences in different ways set (a kind of tree) 6 2 71 5 3 4