CODEWITHSUNDEEP
c++vectoroverloading
incud
incud

Reputation: 551

C++ Overloaded function and errors

In my main class I've got a vector of pointer (vector<Corsa*> listaCorse)

I want insert my Corsa* object inside my ordered vector

So I create an iterator, and I pass him listaCorse.begin(), listaCorse.end(), myPointerToTheObject, &sortFunction)

Resolved: I don't know why, but I just included algorithm and vector, and now it compiles.
I really don't know why, because I included them inside the myhugeclass.h file, but it works, and that's ok
Thank you everyone :)

Problem: sortFunction is a static function inside my 'Corsa' class. And it is overloaded.
The two prototypers are:

bool Corsa::cmpCorse(Corsa *a, Corsa *b)
bool Corsa::cmpCorse(Corsa &a, Corsa &b)



Obviously I want to pass to him the first one, because mine is a vector of pointer
But my compiler doesn't like my code so much, so it says me 'unresolved overload function type'

Can anyone help me? :)
Thank you so much

This is the snippet of code:

// corsa.h
class Corsa{
    ...
    static int cmpCorsa(const Corsa& a, const Corsa& b);
    static int cmpCorsa(const Corsa *a, const Corsa *b);
    ...
}

// myhugeclass.cpp
int MyHugeClass::addCorsa(Corsa *a){
    vector<Corsa*>::iterator low = lower_bound(listaCorse.begin(), listaCorse.end(), c, &Corsa::cmpCorsa);
    listaCorse.insert(low, c);
    return 0;
}

Thank you :)

EDIT: I made a big mistake, but not related tthis error. I passed the wrong function, I should pass static bool Corsa::sortCorsa(Corsa *a, Corsa *b)
Also this function is overloaded

As chris said (thank you chris), I try to do this:

int MyHugeClass::addCorsa(Corsa *c){

    typedef bool(*Func)(const Corsa*, const Corsa*);
    vector<Corsa*>::iterator low = lower_bound(listaCorse.begin(), listaCorse.end(), c, static_cast<Func>(&Corsa::sortCorsa));
    listaCorse.insert(low, c);
    return 0;
}

Now the error changes in [Error] no matching function for call to 'lower_bound(std::vector<Corsa*>::iterator, std::vector<Corsa*>::iterator, Corsa*&, bool (*)(const Corsa*, const Corsa*))'

Upvotes: 2

Views: 569

Answers (3)

Matthieu M.
Matthieu M.

Reputation: 299730

This is an answer, and then maybe not...

When using sorted vectors (or deques) I have often found that using std::lower_bound was not as practical as using std::partial_sort:

// assume vec is sorted
size_t const currentSize = vec.size();

vec.push_back(...); // like usual
// or
std::copy(input.begin(), input.end(), std::back_inserter(vec));

std::partial_sort(vec.begin(), vec.begin() + currentSize, vec.end() /*, comparator*/);

It's as efficient as std::lower_bound on a single insertion, and has the potential to be more efficient when multiple insertions take place.

Note: a call to std::sort also works, and the implementation is usually optimized to take advantage of sorted runs, but it still seems wasteful.

Upvotes: 0

Qaz
Qaz

Reputation: 61900

You can cast it to the right type:

typedef bool(*Func)(const Corsa*, const Corsa*);
vector<Corsa*>::iterator low = lower_bound(..., static_cast<Func>(&Corsa::sortCorsa));

Upvotes: 3

PaulMcKenzie
PaulMcKenzie

Reputation: 35440

Here is a full example that compiles cleanly that uses std::sort. Note the typedef and the cast

#include <algorithm>
#include <vector>
struct Corsa
{
    static bool cmpCorsa(const Corsa& a, const Corsa& b);
    static bool cmpCorsa(const Corsa *a, const Corsa *b);
};

typedef bool (*fn)(const Corsa*, const Corsa*);
int main()
{
   std::vector<Corsa*> C;
   std::sort(C.begin(), C.end(), static_cast<fn>(&Corsa::cmpCorsa));
}

Upvotes: 1

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