Question

I am using a custom Set class that is basically the same as the STL Set class

The problem is that I am somehow implementing it incorrectly and the default comparison function is used rather than a comparison I defined.

Set<Lexicon::CorrectionT> Lexicon::suggestCorrections(Lexicon::MatchesT & matchSet)
{
    Set<CorrectionT> suggest(compareCorr); //ordered Set
    suggestCorrectionsHelper(root, suggest, 0, matchSet.testWord, 0, matchSet.testTime);
    return suggest;
}


int compareCorr(Lexicon::CorrectionT a, Lexicon::CorrectionT b)
{
    if (a.editDistance < b.editDistance)
        return -1;
    else if (a.editDistance == b.editDistance)
            return 0;
    else
        return 1;
}

struct CorrectionT {
    int editDistance; //stackItems
    string suggestedWord; //stackItems
};

Some research:

• The class library
• An issue with the same class – suggested that the STL Set class is used, in this case I might still need help understanding how to define the comparison function, so posting question

I have 19 C2784 errors all relating to some form of “error C2784: ‘bool std::operator ==(const std::_Tree<_Traits> &,const std::_Tree<_Traits> &)’ : could not deduce template argument for ‘const std::_Tree<_Traits> &’ from ‘Lexicon::CorrectionT’

and referencing this code

template <typename Type>
int OperatorCmp(Type one, Type two) {
    if (one == two) return 0;
    if (one < two) return -1;
    return 1;
}

My question: how do you suggest correcting this?

Attempt at changing default definition type:

#include "lexicon.h"

//template <typename Type>
int OperatorCmp(Lexicon::CorrectionT one, Lexicon::CorrectionT two) {
    if (one.editDistance == two.editDistance) return 0;
    if (one.editDistance < two.editDistance) return -1;
    return 1;
}

#endif

Answer 1

The comparison function for STL set must be a Strict Weak Ordering, so that class is not the same as an STL set.

The error indicates the default OperatorCmp is being used, I don’t know why, but you could make that default one work by defining operator< and operator== for your CorrectionT type.