How do you use the push_back function of a vector?

The push_back function in vector is used to add an element to the end of the vector.

The usage is as follows:

1. Create a vector object:

std::vector<int> vec;

1. Add elements using the push_back function.

vec.push_back(1);
vec.push_back(2);
vec.push_back(3);

This will add elements 1, 2, and 3 to the end of the vector sequentially.

Please make sure that the parameter type of the push_back function matches the storage type of the vector. In the above example, the storage type of the vector is int, so we use values of type int as parameters for the push_back function. If the storage type of the vector is a custom class object, you will need to pass an instance of the corresponding class object as a parameter for the push_back function.