I can't figure out why in this code example the std::set container is not ordering the Entities as I expect on the basis of the compare class I defined. Anyone can help me please? Thanks
#include <iostream>
#include <set>
class Entity {
public:
int num;
Entity(int num):num(num){}
bool operator< (const Entity& _entity) const { return (this->num < _entity.num); }
};
struct my_cmp {
bool operator() (const Entity* lhs, const Entity* rhs) const { return (lhs < rhs); }
};
class EntityManager {
private:
std::set<Entity*, my_cmp> entities;
public:
void AddEntity(int num) { entities.insert(new Entity(num)); }
void ListAllEntities() const {
unsigned int i = 0;
for (auto& entity: entities) {
std::cout << "Entity[" << i << "]: num:" << entity->num << std::endl;
i++;
}
}
};
int main(void) {
EntityManager manager;
manager.AddEntity(2);
manager.AddEntity(1);
manager.AddEntity(4);
manager.AddEntity(3);
manager.ListAllEntities();
return 0;
}
Output:
Entity[0]: num:2
Entity[1]: num:1
Entity[2]: num:4
Entity[3]: num:3
I would expect the following output instead:
Entity[1]: num:1
Entity[0]: num:2
Entity[3]: num:3
Entity[2]: num:4
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