由浅入深学习 map 容器 by 彭于斌（ @archibate ） 我负责监督你鞋习 ! 我负责监督你鞋习 ! 本期看点： 用方括号 [ ] 取出 map 元素居然是错误的！ 能不能在遍历的同时删除元素？安全吗？ emplace ， emplace_hint ， try_emplace 的区别？ 课程安排 1. vector 容器初体验 & 迭代器入门 (BV1qF411T7sd) 2 set 容器 & 迭代器分类 (BV1m34y157wb) 3. string ， string_view ， const char * 的爱恨纠葛 (BV1ja411M7Di) 4. 万能的 map 容器全家桶及其妙用举例 ( 本期 ) 5. 函子 functor 与 lambda 表达式知多少 6. 通过实战案例来学习 STL 算法库 7. C++ 标准输入输出流 & 字符串格式化 8. traits 第一章：读取与写入 我负责监督你鞋习 ! 我负责监督你鞋习 ! map 查找元素的两个接口 • map 提供了两个查找元素的接口，一曰 [] ，二曰 at 。 • 那么他们两个又有什么区别呢？很多新手都分不清他俩，可能只认识 [] 。 读取 map 元素 • map m; • 读取 map 中指定键值的元素有两种方法。 • val = m[“key”];

its environment ● Enter: The occupancy map ○ A data structure used to represent the environment around a robot in terms of how “occupied” the cells in the map are Clip from https://www.youtube.com/watch occupancy map ○ A data structure used to represent the environment around a robot in terms of how “occupied” the cells in the map are ● Assumption: The robot knows its location in the occupancy map at all occupancy map ○ A data structure used to represent the environment around a robot in terms of how “occupied” the cells in the map are ● Assumption: The robot knows its location in the occupancy map at all

Introduction Persistent Hash Map Persistent Transactional Data Structures Live Demonstration ReferencesIntroduction Persistent Hash Map Persistent Transactional Data Structures Live Demonstration References References Overview Introduction Persistent Memory Use-Cases Pitfalls Persistent Hash Map Design Goals and Methodology Persistence Performance Results Persistent Transactional Data Structures Design Demonstration A Persistent Hash Map for Graph Processing Workloads and a Methodology for Persistent Transactional Data Structures 2IntroductionIntroduction Persistent Hash Map Persistent Transactional Data

environment This is a map of a make-believe distribution facility that is: 0.8 km long 0.4 km deep 51The operating environment This is a spatial graph extracted from the map. 52The operating environment std::for_each #include <map> // std::map, std::multimap #include // std::apply class Graph { private: std::multimap adjacencies_; std::map std::for_each #include <map> // std::map, std::multimap #include // std::apply class Graph { private: std::multimap adjacencies_; std::map

DECLARE_DYNCREATE, DECLARE_DYNAMIC, IMPLEMENT_DYNAMIC, IMPLEMENT_DYNCREATE, DECLA RE_MESSAGE_MAP, BEGIN_MESSAGE_MAP, END_MESSAGE_MAP。感激不尽，因为 我常搞不清楚。 titoni：可参考侯俊杰着的深入浅出MFC 2/e 第三章，第八章及第九章，书上的讲解可 以让你有很大的收获。 好象世 視窗類別之註冊與視窗之誕生 / 016 訊息迴路 / 018 視窗的生命㆗樞 - 視窗函式 / 019 訊息映射（Message Map）雛形 / 020 對話盒的運作 / 022 模組定義檔（.DEF） / 024 資源描述檔（.RC） / 024 視窗顯示與更新 / 389 CWinApp::Run - 程式生命的活水源頭 / 390 把訊息與處理函式串接在㆒起：Message Map 機制 /394 來龍去脈總整理 / 397 Callback 函式 / 398 目 錄 19 * 閒置時間（idle time）的處理：OnIdle

bool IsInMap(const std::string& host) const { return host_int_map_.contains(host); } private: std::map host_int_map_; }; #include bool HasKnownHost(const A& a) { return to string But this now causes memory allocation at runtime  Optimization: Searching through the map 49 // In header file std::span GetKnownHosts(); // In header const std: bool IsInMap(const std::string& host) const { return host_int_map_.contains(host); } private: std::map host_int_map_; }; bool HasKnownHost(const A& a) { return std::ranges::any_of(

key - Iteration over unordered range of values Sparse Matrix - Similarities to std::unordered_map 75 [“x”] 120 [“y”] 121 [“z”] 122 [“b”] 98[DISTRIBUTION STATEMENT A] This material has been approved key - Iteration over unordered range of values Sparse Matrix - Similarities to std::unordered_map 76 [“x”] 120 [“y”] 121 [“z”] 122 [“b”] 98[DISTRIBUTION STATEMENT A] This material has been approved key - Iteration over unordered range of values Sparse Matrix - Similarities to std::unordered_map 77 [“x”] 120 [“y”] 121 [“z”] 122 [“b”] 98[DISTRIBUTION STATEMENT A] This material has been approved

BCL::init(); BCL::HashMap map(BCL::nprocs()); if (BCL::rank() == 0) { for (int i = 0; i < BCL::nprocs(); i++) { map.insert({std::to_string(i), i}); } } ... }Data BCL::init(); BCL::HashMap map(BCL::nprocs()); if (BCL::rank() == 0) { for (int i = 0; i < BCL::nprocs(); i++) { map.insert({std::to_string(i), i}); } } ... } BCL::init(); BCL::HashMap map(BCL::nprocs()); if (BCL::rank() == 0) { for (int i = 0; i < BCL::nprocs(); i++) { map.insert({std::to_string(i), i}); } } ... }Data

Standard Library  String Formatting Improvements  Standard Library Modules  std::flat_(multi)map / std::flat_(multi)set  std::mdspan  std::generator  basic_string(_view)::contains()  Construct Standard Library  String Formatting Improvements  Standard Library Modules  std::flat_(multi)map / std::flat_(multi)set  std::mdspan  std::generator  basic_string(_view)::contains()  Construct Standard Library  String Formatting Improvements  Standard Library Modules  std::flat_(multi)map / std::flat_(multi)set  std::mdspan  std::generator  basic_string(_view)::contains()  Construct

eliminate items to create a list of the same number or fewer items of the same type. • std::copy_if • Map - take a list of items of one type and create a list of the same size with all items converted to Functions: Mashing bananas All Bananas Ripe Bananas Peeled Bananas filter(IsBanana) filter(IsRipe) map(Peel) Mashed Bananas reduce(Mash) Current Inventory Ingredient MakeBananaMash() { auto currentInventory end(sourceList), std::back_inserter(filteredList),filter); return filteredList; }Composable Functions: Filter, Map Ingredient MakeBananaMash() { const auto currentInventory = GetCurrentInventory(); const auto allBananas=