qt的swap源码。
template <typename T>
inline void qSwap(T &value1, T &value2)
{
const T t = value1;
value1 = value2;
value2 = t;
}
qt文档又说:The sort algorithm is efficient on large data sets. It operates in linear-logarithmic time, O(n log n).
这样移动大的对象还是很影响效率的吧