Difference between revisions of "Intermediate C++ Game Programming Tutorial 24"
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** Use case: ensure that there are no duplicates in a set | ** Use case: ensure that there are no duplicates in a set | ||
* The <code>std::multimap</code> and <code>std::multiset</code> classes [https://youtu.be/JlPsCoCO99o?t=21m28s 21:28] | * The <code>std::multimap</code> and <code>std::multiset</code> classes [https://youtu.be/JlPsCoCO99o?t=21m28s 21:28] | ||
| − | ** Map has unique keys, with multimap you can insert multiple elements with the same key | + | ** Map has unique keys, with multimap you can insert multiple elements with the same key |
| + | ** This enables operations like <code>std::multimap::equal_range</code> that returns a pair of iterators (begin and end) of the range where these elements have that same key | ||
| + | ** <code>std::multimap::count</code> will return the number of elements with specific key | ||
| + | * Practical example of multimap use case [https://youtu.be/JlPsCoCO99o?t=22m30s 22:30] | ||
| + | |||
</div> | </div> | ||
[https://youtu.be/LsjFAx-dG5I Tutorial 24.2] | [https://youtu.be/LsjFAx-dG5I Tutorial 24.2] | ||
Revision as of 04:14, 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
[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
- [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.
