An Introduction to Data Structures

Other Standard Containers

The C++ set ignore duplicates; if you insert an element into the set that is already present, the insertion has no effect.
The count function returns the number of times that an element is contained in a set (should always be 1).
```
set<string> s;

s.insert("Tom");
s.insert("Tom");
cout << s.count("Tom") << "\n"; /* displays 1 */
```
If you want to be able to keep track of multiple occurrences of identical values, use a multiset instead.

The count function works for multiset, with expected results.

multiset<string> m;

m.insert("Tom");
m.insert("Tom");
cout << m.count("Tom") << "\n"; /* displays 2 */