Difference between revisions of "Intermediate C++ Game Programming Tutorial 24"
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** An even better way to insert is through <code>map.emplace[]</code> operation; iit will construct the pair in-place. | ** An even better way to insert is through <code>map.emplace[]</code> operation; iit will construct the pair in-place. | ||
** For lookup, you can use square braces, <code>map[x]</code> will return a reference to the corresponding value | ** For lookup, you can use square braces, <code>map[x]</code> will return a reference to the corresponding value | ||
| − | + | ** Note: a lookup with ha new key value will create that element in the map with the default constructed ValueType value | |
</div> | </div> | ||
Revision as of 03:17, 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
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std::unordered_mapkey requirements - Hash combining
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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 7:35-
map.insert()takes a pair typestd::pair<KeyType,ValueType>, the Map's elements - C++ can deduce the pair Type, so
map.insert({keyX,valueXYZ});with curly braces will do the job - An even better way to insert is through
map.emplace[]operation; iit will construct the pair in-place. - For lookup, you can use square braces,
map[x]will return a reference to the corresponding value - Note: a lookup with ha new key value will create that element in the map with the default constructed ValueType value
-
- [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.
