Template operator overloading

Question

So I am writting a code where I am sorting something. And I have my definition in a class term.cpp

friend bool operator<(Term T1, Term T2);

Then in a Template I was provided with we have a implementation of the merge sorting algorithm as

void SortingList<T>::merge_sort(int (*compare)(T T1, T T2));

Now suppose I have the following

SortingList<Term> randomList;
randomList.merge_sort(???);

So my question is what do I put in the ??? I tried

randomList.merge_sort(Term::operator<(Term T1, Term T2));

but it did not work and i'm confused, I do not know how the compiler wants the operator put inside the merge_sort implementation

Bo Persson · Accepted Answer · 2017-11-25 02:23:48Z

2

You would have to create a compare wrapper if the requirement is to return an int. This would convert the bool returned from operator<

int compareTerm(Term T1, Term T2)
{
   if (T1 < T2)
      return -1;
   else if (T2 < T1)
      return 1;
   else
      return 0;
}

Then just pass compareTerm to merge_sort.

answered Nov 25, 2017 at 2:23

Bo Persson

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3 Comments

I see and I actually wrote a function called compareTerm ... that makes since

What if i wanted to pass in a value to comparTerm like comparTerm(Term,Term,int) then how would I call merge_sort?

Then you could use a functor object instead of a function, and pass extra parameters to its constructor.