Difference between revisions of "Intermediate C++ Game Programming Tutorial 24"
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** <code>insert</code> or <code>emplace</code> with a key that already exists will NOT override the existing value: <code>std::map::emplace</code> returns a <code>std::pair<iterator,bool></code> where the bool inidicates whether an insertion took place | ** <code>insert</code> or <code>emplace</code> with a key that already exists will NOT override the existing value: <code>std::map::emplace</code> returns a <code>std::pair<iterator,bool></code> where the bool inidicates whether an insertion took place | ||
** <code>map.find("xyz")<code> returns an iterator to the element if it exitst, and an iterator to <code>map.end()</code> if it doesn't exist (useful to check if a key already exists) | ** <code>map.find("xyz")<code> returns an iterator to the element if it exitst, and an iterator to <code>map.end()</code> if it doesn't exist (useful to check if a key already exists) | ||
| + | ** <code>std::map</code> comes with iterators and because it is a sorted map, when you iterate over its elements with <code>for (auto& el : map)</code>, it will be in order (of the keys) | ||
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Revision as of 03:29, 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
- [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.
