[問題] 為什麼類別不需建立物件就可使用
// comparator predicate: returns true if a < b, false otherwise
struct IntComparator
{
bool operator()(const int &a, const int &b) const
{
return a < b;
}
};
...
// An overload of std::sort is:
template <class RandomIt, class Compare>
void sort(RandomIt first, RandomIt last, Compare comp);
...
int main()
{
std::vector<int> items { 4, 3, 1, 2 };
std::sort(items.begin(), items.end(), IntComparator());
return 0;
}
sort的第三個引數，應該是一個Compare 類別的物件，但是在main裡面，
卻直接用IntComparator()當作引數，請問一下這是怎麼回事，應該用什麼關鍵字來查詢？
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