CODEWITHSUNDEEP
c++sortingc++11vectorlambda
wakanada
wakanada

Reputation: 115

Sorting objects vector with lambda, not sorting in the end

I'm trying to write a sort function for vectors using lambda, and I've seen this suggested at so many places, but I've always had problems doing this.

std::sort(eventvec.begin(), eventvec.end(), [](const event& lhs, const event& rhs) {
    return lhs.getim < rhs.getim;});

I had multiple errors while writing it and then I kind of stacked it on a function within a function as it needed a static function.

The functions declared in the class are:

double event::getut() { return unift; }

static double getim(event &a) { return a.getut(); }

In the end the sorting is not in order at all. There are negative values as well in the attribute. Any suggestions?

Upvotes: 0

Views: 111

Answers (1)

Caleth
Caleth

Reputation: 62719

You are sorting your events by the address of event::getim, which is the same for every event.

I think you mean to call a member function of event, which needs to be callable from a const event

double event::getut() const { return unift; }

std::sort(eventvec.begin(), eventvec.end(), [](const event& lhs, const event& rhs) {
return lhs.getut() < rhs.getut(); });

Upvotes: 3

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