Difference between revisions of "Intermediate C++ Game Programming Tutorial 15"
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* Example code for handling operations on different types of containers, i.e.<br /><code>template<typename Iter1, typename Iter2, typename Iter3></code><br /><code>void sum(Iter1 in1, Iter1 end1, Iter2 in2, Iter3 out){...}</code> [https://youtu.be/h5aFJJp1Stw?t=20m41s 20:41] | * Example code for handling operations on different types of containers, i.e.<br /><code>template<typename Iter1, typename Iter2, typename Iter3></code><br /><code>void sum(Iter1 in1, Iter1 end1, Iter2 in2, Iter3 out){...}</code> [https://youtu.be/h5aFJJp1Stw?t=20m41s 20:41] | ||
* Example applying a <code>back_insert_iterator</code>, calling the <code>sum</code> function like so:<br /><code>sum( vi.begin(), vi.end(), vf.begin(), std::back_inserter(lf) )</code> [https://youtu.be/h5aFJJp1Stw?t=22m22s 22:22] | * Example applying a <code>back_insert_iterator</code>, calling the <code>sum</code> function like so:<br /><code>sum( vi.begin(), vi.end(), vf.begin(), std::back_inserter(lf) )</code> [https://youtu.be/h5aFJJp1Stw?t=22m22s 22:22] | ||
− | * Example code using | + | * Example code using Stream iterators [https://youtu.be/h5aFJJp1Stw?t=23m36s 23:36] |
== Answer to erase puzzle == | == Answer to erase puzzle == |
Revision as of 04:58, 23 September 2019
Iterators are just fancy pointers for containers. In this video we learn how to use iterators, what they're good for, and why we go through all this goddamn trouble in the first place (answer: because they make my dick hard).
Contents
Topics Covered
- Iterator operations (increment/decrement, dereference, add/sub, etc.)
- Getting iterators from containers (begin/end)
- Sequence ranges [closed,open)
- Container manipulation functions (erase/insert)
- Iterators and template algorithms (generic algorithms)
- Iterator categories (random access/bidirectional/forward etc.)
- const_iterator (cbegin/cend) & reverse iterators (rbegin/rend)
- Free iterator functions (std::begin/end/advance/next/prev)
- Iterator adapters (back_inserter, ostream_iterator)
Video Timestamp Index
- Why should I care about iterators? 0:21
- What are iterators? 0:49
- Valid range for an iterator [first,last) 1:27
- What is the type of an iterator / iterator member type definitions 1:55
- Getting an iterator from a container, using the example
std::vector<int>::iterator i = v.begin();
2:34 - Simple
for
loops with iterators & iterator arithmetic 3:52 - Iterator protection and code safety when misused / out of bounds / invalidated 6:48
- Container manipulation function
erase
7:20 - Iterators that return iterators (recovering from an invalidation), e.g.
i = v.erase(i);
10:17 - Container manipulation function
insert
/emplace
11:45 - Why not just use indices? Iterators and template algorithms (generic algorithms) 12:36
- Introducing the
forward_list
container 13:40 - Template a function on an Iterator: writing a generic function that can be applied to any type of container, e.g.
template<typename Iter>
void print(Iter begin, Iter end){...}
14:35 - Introducing the Algorithms library 15:16
- The five types of iterators: input, output, forward, bidirectional, random access 15:29
- Constant interators 16:26
- Reverse interators 17:39
- Free functions & iterators in the Standard library (STL)
std::begin(container_object)
, works on C-arrays so generic Algorithms can be applied 18:22 - Special purpose iterators: Iterator adapters (
back_inserter
,ostream_iterator
) 20:32 - Example code for handling operations on different types of containers, i.e.
template<typename Iter1, typename Iter2, typename Iter3>
void sum(Iter1 in1, Iter1 end1, Iter2 in2, Iter3 out){...}
20:41 - Example applying a
back_insert_iterator
, calling thesum
function like so:sum( vi.begin(), vi.end(), vf.begin(), std::back_inserter(lf) )
22:22 - Example code using Stream iterators 23:36
Answer to erase puzzle
The reason why we do not increment the iterator i
in the for loop, but instead increment it conditionally in the body of the loop is, if we erase an element, the returned iterator will point to the next element after the erased one, and if we were incrementing every iteration of the loop, it would skip all elements that immediately follow an erased element. Instead, we only increment if we did not erase an element, and this ensures that all elements are tested.
Homework
Modify our linked list stack to work with range based for loops. You are not allowed to modify any code outsize of the Stack
class. If you want an extra challenge after completing Level 1, you can uncomment the code for Level 2 and try to get it to compile as well.
Links
Iterator Category Reference
Custom Iterator Example