vector使用

对于vector，它的存储结构和数组一样，连续空间。对于vector类型，它的数据成员有三个：

iterator start;
iterator finish;
iterator end_of_storage;

其增长方式是两倍增长。由于存储空间连续，vector的迭代器本质上仍然是类型的指针。明白这点，以上三个数据成员就非常好理解。start，finsh分别表示正在使用的空间指针。而end_of_storage则表示已经申请到的空间的末尾。

构造、析构、以及赋值

(constructor)
Construct vector (public member function )构造函数

依据函数参数的分类	具体函数
default (1)	vector(); explicit vector (const allocator_type& alloc);
fill (2)	explicit vector (size_type n, const allocator_type& alloc = allocator_type()); vector (size_type n, const value_type& val, const allocator_type& alloc = allocator_type());
range (3)	template < class InputIterator> vector (InputIterator first, InputIterator last, const allocator_type& alloc = allocator_type());
copy (4)	vector (const vector& x); vector (const vector& x, const allocator_type& alloc);
move (5)	vector (vector&& x); vector (vector&& x, const allocator_type& alloc);
initializer list (6)	vector (initializer_list<value_type> il,const allocator_type& alloc = allocator_type());

Note:

拷贝构造函数(copy,构造函数参数包含vector)需要定义的值类型与拷贝的值类型一致，并且是深拷贝，会开辟新空间。
move型构造函数，移动构造函数，C++11新特性，可以减少内存的分配与释放。

(destructor)
Vector destructor (public member function )
operator=
Assign content (public member function )
copy (1) vector& operator= (const vector& x);
move (2) vector& operator= (vector&& x);
initializer list (3) vector& operator= (initializer_list<value_type> il);
assign
range (1) template
void assign (InputIterator first, InputIterator last);
fill (2) void assign (size_type n, const value_type& val);
initializer list(3) void assign (initializer_list<value_type> il);

普普通通的操作符重载以及赋值函数

元素访问

访问方式	具体函数
at()	//带有边界检查的元素访问方式 reference at( size_type pos ); const_reference at( size_type pos ) const;
operator[]	reference operator[ ] ( size_type pos ); const_reference operator[ ] ( size_type pos ) const;
front	// 访问第一个元素 reference front(); const_reference front() const;
back	//访问最后一个元素 reference back(); const_reference back() const;
data	//直接访问隐藏的数组，注意与string不同这里有T * 的重载，而string只有返回const T* 的重载 T* data(); (since C++11) const T* data() const;(since C++11)

迭代器

begin() cbegin() //const iterator	returns an iterator to the beginning (public member function)
end() cend() //const iterator	returns an iterator to the end (public member function)
rbegin() crbegin() //const iterator	returns a reverse iterator to the beginning (public member function)
rend() crend() //const iterator	returns a reverse iterator to the end (public member function)

容量与大小

Capacity
bool empty() const;	checks whether the container is empty (public member function) 检验是否存储的数据为0个，若为0,返回true,否则返回false
size_type size() const;	returns the number of elements (public member function) 当前存储的数据大小（个数）
size_type max_size() const;	returns the maximum possible number of elements (public member function) 存储该类型的最大数目
void reserve( size_type new_cap );	reserves storage (public member function)
size_type capacity() const;	returns the number of elements that can be held in currently allocated storage (public member function) 当前所申请的内存空间大小
void shrink_to_fit(); //(C++11)	reduces memory usage by freeing unused memory (public member function) 这个函数会申请当前大小的空间，并转移数据

vector的修改

Modifiers
void clear();	clears the contents (public member function) void clear() noexcept; 清除过后，beign()==end(),但是size()==0,capacity()等于原来的空间
insert()	inserts elements (public member function) 返回的是插入元素的位置（迭代器） single element (1) iterator insert (const_iterator position, const value_type& val); fill (2) iterator insert (const_iterator position, size_type n, const value_type& val); range (3) template < class InputIterator> iterator insert (const_iterator position, InputIterator first,InputIterator last) move (4) iterator insert (const_iterator position, value_type&& val); initializer list (5) iterator insert (const_iterator position, initializer_list<value_type> il);
emplace() //C++11	constructs element in-place (public member function) 根据要插入的位置，以及各参数，构造一个新元素插入，返回的是插入元素的位置（迭代器） template< class… Args > iterator emplace( const_iterator pos, Args&&… args );
erase()	erases elements (public member function) 返回的是最后一个被删除元素后一个元素 1.single element iterator erase( iterator pos ); iterator erase( const_iterator pos ); 2.range iterator erase (const_iterator first, const_iterator last); iterator erase (const_iterator first, const_iterator last);
push_back()	adds an element to the end (public member function) void push_back (const value_type& val); void push_back (value_type&& val);
emplace_back() //C++11	constructs an element in-place at the end (public member function) template <class… Args> void emplace_back (Args&&… args);
pop_back()	removes the last element (public member function) void pop_back();
resize()	changes the number of elements stored (public member function) void resize (size_type n); void resize (size_type n, const value_type& val)
swap()	swaps the contents (public member function) 交换两个vector的内容 void swap (vector& x);

Reference

[1]https://www.bilibili.com/video/av45108908

[2]http://www.cplusplus.com/reference/vector/vector/

[3]https://en.cppreference.com/w/cpp/container/vector

原文链接: https://www.cnblogs.com/maricat4/p/14710712.html

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