Difference between revisions of "Intermediate C++ Game Programming Tutorial 24"
From Chilipedia
(→Video Timestamp Index) |
(→Video Timestamp Index) |
||
| Line 18: | Line 18: | ||
== Video Timestamp Index == | == Video Timestamp Index == | ||
| − | [https://youtu.be/JlPsCoCO99o Tutorial 24.1] | + | [https://youtu.be/JlPsCoCO99o Tutorial 24.1]: The ordered associative containers |
<div class="mw-collapsible mw-collapsed"><br /> | <div class="mw-collapsible mw-collapsed"><br /> | ||
* The <code>std::map<KeyType,ValueType></code> class [https://youtu.be/JlPsCoCO99o?t=0m46s 0:46] | * The <code>std::map<KeyType,ValueType></code> class [https://youtu.be/JlPsCoCO99o?t=0m46s 0:46] | ||
| Line 85: | Line 85: | ||
** The problem with <code>find()</code> on a multimap, is that if there are several elements with key in the ccontainer, any of them may be returned | ** The problem with <code>find()</code> on a multimap, is that if there are several elements with key in the ccontainer, any of them may be returned | ||
</div> | </div> | ||
| − | [https://youtu.be/LsjFAx-dG5I Tutorial 24.2] | + | [https://youtu.be/LsjFAx-dG5I Tutorial 24.2]: The unordered associative containers |
* [WORK-IN-PROGRESS] | * [WORK-IN-PROGRESS] | ||
Revision as of 04:34, 20 January 2020
Associative containers are super useful, both as a convenient fast way to create dictionary or mapping for real-world problems like managing game resources, and as a data structure to help solve more abstract algorithmic computer science problems. And hash tables are fast as balls.
Contents
[hide]Topics Covered
Part 1
-
std::mapcontainer interface - Binary tree data structure
-
std::mapkey requirements (comparison) -
std::mapgotchas (std::remove_ifandconstkeys) -
std::set -
std::multimapandstd::multiset
Part 2
- Hash table performance vs. binary tree performance
- Hash table data structure
-
std::unordered_mapkey requirements - Hash combining
-
std::unordered_mapbucket interface and hashing policy - When to choose
std::mapoverstd::unordered_map
Video Timestamp Index
Tutorial 24.1: The ordered associative containers
[Expand]
- The
std::map<KeyType,ValueType>class 0:46
- The Binary tree data structure 2:46
- A look at the
std::mapcppreference.com documentation: Insert, Lookup, Find 7:35
- Requirements on KeyType 14:30
-
std::mapcppreference.com documentation continued: Erase 15:28
- Two <<important>> things to know when working with associative containers 16:04
- The
std::set<KeyType>class 20:00- With a set, you only have keys, and a unique entry for each unique key
- Use case: ensure that there are no duplicates in a set
- The
std::multimapandstd::multisetclasses 21:28- Map has unique keys, with multimap you can insert multiple elements with the same key
- This enables operations like
std::multimap::equal_rangethat returns a pair of iterators (begin and end) of the range where these elements have that same key -
std::multimap::countwill return the number of elements with specific key
- Practical example of multimap use case 22:30
- Implementation example of a custom Comparison functor for the
Vei2class (2D coordinate vector).
- - Chili's choice for ordering (used in the body of the functor):
- -
return (lhs.x == rhs.x) ? lhs.y < rhs.y : lhs.x < rhs.x;
- Example of how to find and print multiple elements in a multimap using
equal_range()
- Implementation example of a custom Comparison functor for the
- multimap does not have an index operator
[]25:21- When you do a lookup on a multimap, you should use
equal_range() - The problem with
find()on a multimap, is that if there are several elements with key in the ccontainer, any of them may be returned
- When you do a lookup on a multimap, you should use
Tutorial 24.2: The unordered associative containers
- [WORK-IN-PROGRESS]
Homework Assignment
The homework for this video is to enable use of a custom datatype in unordered_map hashing over multiple (4) members of that datatype. The solution video is here.
