vector<int>&的用法

A vector is a container in C++ that is used to store a sequence of elements of the same type. A vector can be created by including the vector header file and using the following syntax:

vector<int> v;

This creates an empty vector of integers named v. Elements can be added to the vector using the push_back() function:

v.push_back(4);
v.push_back(5);
v.push_back(6);

This adds the integers 4, 5, and 6 to the vector v. Elements can be accessed using the square bracket operator []:

cout << v[0] << endl; // prints 4
cout << v[1] << endl; // prints 5
cout << v[2] << endl; // prints 6

The size of the vector can be obtained using the size() function:

cout << v.size() << endl; // prints 3

Vectors can also be initialized with a set of elements:

vector<int> v = {1, 2, 3, 4, 5};

And elements can be removed from the end of the vector using the pop_back() function:

v.pop_back(); // removes the element 5 from the end of the vector