#include<vector>
using std::vector;
//Vector is a container.
//It has a collection of same type objects.
//******************************************************
//Defining and Initializing vectors
vector<int> ivec; //Initially empty
//give ivec some values
vector<int> ivec2(ivec); //copy elements from ivec to ivec2
vector<int> ivec3 = ivec2; //The same as above.
//In C++11
vector<int> ivec4 = {1,2,3,4}; //List initializing a vector
vector<int> ivec5{1,2,3,4};
vector<int> ivec6(10, -1); //ten int elements, each initialized to -1
//vector<Type> var(count, value);
vector<int> ivec7(10); //10 elements, each initialized to 0
//vector<Type> v(n); v has n copies of a value-initialized object.
//******************************************************
//Adding elements to a vector
ivec.push_back(1);
//******************************************************
//other operations
v.empty();
v.size();
//return the number of objects in v. The type of return value is not int, but vector<Type>::size_type.
v[n]; //just like the usage in array.
v1 = v2; //Replaces the elements in v1 with a copy of v2.
v1 == v2; //if v1 and v2 have the same objects, True
<, <=, >, >=//just like the compare in string
