Sometimes you need a vector or list of associations. An association is a pair of values that has some link in the problem model. For example, a student and grade are associated with each other.

Suppose you want to maintain the grade of each student. You need a list of all the students together with their grades. This can be done by using , which is simply a struct with two values.

Here’s the basic building block of a map:

vector > stu_gra;string stu;int gra;do{   cin >> stu >> gra;   stu_gra.push_back(pair(stu,gra) );} while (stu != "end");

When you want to retrieve the values stored in the vector (or list) of pairs, you write:

vector > :: iterator i = stu_gra.begin();while(i != stu_gra.end()){   cout << "Student : " << i->first << ", Grade : " << i->second << endl;   i++;}

The first and second members are used to access the respective elements of pair.