Sort Dates using HeapSort in C++

I have done the part in sorting integers using heapsort. But I am struggling in building the logic to sort dates.

For example: February 22 1956,March 24 1856,March 22 1856.

The output I required is: March 22 1856, March 24 1856,February 22 1956.

How can I do this in c++ using heapsort?