Difference between revisions of "Intermediate C++ Game Programming Tutorial 24"

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(Video Timestamp Index)
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*:- With an iterator range, idem
 
*:- With an iterator range, idem
 
*:- By key through <code>map.erase(const KeyType& key)</code>; this operation returns the number of elements erased (in <code>size_type</code>)
 
*:- By key through <code>map.erase(const KeyType& key)</code>; this operation returns the number of elements erased (in <code>size_type</code>)
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* Important to know when working with associative containers [https://youtu.be/JlPsCoCO99o?t=16m04s 16:04]
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** <code>std::remove_if</code> does not work with associative containers.
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*:- You have to iterate over the elements with <code>for( auto i = map.begin(); i != map.end();)</code>
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*:- And apply <code>it = map.erase(...)</code> in the body of your <code>if</code> logic, and <code>++i</code> outside the <code>if</code> block.
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** Example: removing all elements whose keys have names with more than 2 characters:
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*:- <code>std::remove_if( map.begin(),map.end(),[]( auto& el ){ return el.first.size() > 2; } );</code>
 
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Revision as of 03:56, 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.

Topics Covered

Part 1

  • std::map container interface
  • Binary tree data structure
  • std::map key requirements (comparison)
  • std::map gotchas (std::remove_if and const keys)
  • std::set
  • std::multimap and std::multiset

Part 2

  • Hash table performance vs. binary tree performance
  • Hash table data structure
  • std::unordered_map key requirements
  • Hash combining
  • std::unordered_map bucket interface and hashing policy
  • When to choose std::map over std::unordered_map

Video Timestamp Index

Tutorial 24.1

[Expand]
  • The std::map<KeyType,ValueType> class 0:46
  • The Binary tree data structure 2:46
  • A look at the std::map cppreference.com documentation: Insert, Lookup, Find 7:35
  • Requirements on KeyType 14:30
  • std::map cppreference.com documentation continued: Erase 15:28
  • Important to know when working with associative containers 16:04

Tutorial 24.2

  • [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.

Supplementary Link

See also