C++ STL: Set

📅 2010-Mar-05 ⬩ ✍️ Ashwin Nanjappa ⬩ 🏷️ cpp, sets, stl ⬩ 📚 Archive

One can create and use a STL vector of objects of a class without any extra code. To do the same with a STL set of objects of a class one needs to add a comparison function to the class. This is required because a set keeps its elements sorted.

A bare bones example:

#include <set>

class MyObj
{
    public:
        int _item;
        MyObj::MyObj(int item) : _item(item) {}

        // Comparison
        bool MyObj::operator < (const MyObj& other) const
        {
            return _item < other._item;
        }
};

int main()
{
    std::set<MyObj> mySet;
    mySet.insert(10);
    mySet.insert(7);

    return 0;
}