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C++ primer 第九章笔记

section 9.1 Overview of Sequential Container

1. Sequential Containter Types:
   
   • vector: flexible size, fast random access, slow insertion and deletion other than at back
   • deque:double-ended queue, fast random access, fast insert/delete at back and front
   • list:doubly linked list, only bidirectional sequential access, fast delete/insert at any point
   • forward_list:singly linked list, only sequential access, fast delete/insert at any point
   • array:fixed size, fast random access, can’t add or remove elements
   • string: specialized container, similar to vector that contains characters.
2. Which sequential container to use: rule of thumb
   
   • use vector unless you have a reason to use others
   • use list or forward_list if program has lots of small elements and space doesn’t matter.
   • insert/delete in the middle: list/forward_list
   • insert/delete at front and back: deque
   • note that some insertion in the middle can use insert and sort instead

section 9.2 Overview of Sequential Container

1. iterator range: [begin, end)
2. begin, cbegin(const), rbegin(reverse)
3. XX.begin() is overloaded as const and non-const, depends on whether the members of objects are const or not.
4. initialize a container using copy demands that container type and element type are identical
5. array <int, 41> arr;
6. 6 ways to initialize:
7. C c1;
8. C c1(c2); C c1 = c2;
9. C c1{1, 2, 3}; C c1 = {1, 2, 3};
10. C c1(begin, end);
11. C c1(n)
12. C c1(n, c)

section 9.3 Sequential Container Operations

1. seq.assign(i1)不能使用左侧的iterators，references,pointers
2. swap 保证O(1)时间复杂度，不会无效左侧的iterators，references,pointers。string除外,array除外（改变内容）
3. emplacecalls constructor

c.emplace_back("978-0590353403", 25, 15.99);c.push_back(Sales_data("978-0590353403", 25, 15.99));

1. c.back(), c.front(), c.at(n), c[n] 都返回reference.
   
auto &v = c.back();

2. calling front or back when empty and c[n], n >= c.size() will cause programming error. at is safe
3. pop_back and pop_front return void, so get things done before deleting.
4. resize(n), value initialized.(resize(n,t))
5. reserve(n), allocate n elements in memory
6. shrink_to_fit(), a request to return exceeded memory.

section 9.5 Additonal string Operations

1. Additonal ways to construct a str
2. string s(cp, n) a copy of n characters from a const char*(null terminated)
3. string s(s2, pos2), a copy of the characters starting from position pos2(undefined if s2.size() < pos2)
4. string s(s2, pos, len2), a copy of len2 characters starting from position pos2. copies at most s2.size() - pos2 characters

section 9.6 Container Adaptors

1. stack, queue, priority_queue.
2. adaptors can not use operations of underlying container type
3. stack can use vector, list, deque(by default). queue can use list and deque(default). priority_queue can use vector(default) and deque(not list because of random access)
4. queue: q.front() and q.back(); priority_queue: q.top()
5. 注意： s.end()不能再加任何数，不然会报错！！！