STL vector

Vectors are sequence containers representing arrays that can change in size.

Constructor

vector可以使用四种参数方法构造

//1. 无参数，默认构造函数，构造一个空的vector
vector();
// 2. 数量(num)和值(val) - 构造一个初始放入num个值为val的元素的Vector 
vector( size_type num, const TYPE &val );
// 3. vector(from) - 构造一个与vector from 相同的vector 
vector( const vector &from );
4. 迭代器(start)和迭代器(end) - 构造一个初始值为[start,end)区间元素Vector(注:半开区间). 
vector( input_iterator start, input_iterator end );

vector<int> v1(5, 9);
vector<int> v2(v1);// copy constructor
vector<int> v3(v1.begin(), v1.end() - 1);

迭代器

member function	effect
begin()	return iterator to beginning(the index 0)
end()	return itetator to end (the position next to the last one )
rbegin()	Return reverse iterator to reverse beginning(the last one)
rend()	Return reverse iterator to reverse end(the position before the first one)

for(vector<int>::iterator it = v1.begin(); it != v1.end(); it++){
    cout << *it << " ";
}

cout << endl;
	
for(vector<int>::reverse_iterator it = v1.rbegin(); it != v1.rend(); it++){
	cout << *it << " ";
}
cout << endl;

capacity

member function	effect
size()	return size
max_size()	return maximum size
empty()	test wether vector is empty

cout << v1.max_size() << endl;
while(!v1.empty()){
	cout << v1.back() << endl;
	v1.pop_back();
}

element access

member function	effect
front()	access the first element
back()	access the last element
at()	access element

cout << v2.front() << endl;
cout << v2.back() << endl;
cout << v2.at(2) << endl;// 输出第三个元素，也就是index为2的元素

Modifiers:

member function	effect
push_back()	add element at the end
pop_back()	delete the last element
insert()	insert element
erase()	rease element
clear()	clear content

v1.push_back(1);
v1.push_back(2);
v1.push_back(3);
v1.pop_back();
vector<int> v;
v.insert(v.begin(),10);//插入位置是迭代器
v.insert(v.begin(),2,20);
v.insert(v.begin(),v1.begin(),v1.begin()+2);
v.erase(v.begin());//删除某个元素
v.erase(v.begin(),v.end());// 删除某一段元素