inline bool operator < declaration

[bikram07]

Hi all, i am doing the following.

struct Adjacent
{
string name1;
int distance1,fare1;

};

inline bool operator<(const Adjacent &m, const Adjacent &n)
{
return (m.distance1 < n.distance1) && (m.fare1 < n.fare1);
}


I want to sort the two queue's one by fare and other by distance at same time or in same program. May be i need to return boolean operator( if i am right ) for each operation. I tried some combination but dint work any.
in the case above it displays the result according to fare sort.

Someone please help me for this ASAP.. Thanks alot.

[kbw]

You need to pass a sort predicate to each container, rather than using a global operator< for your type.

[bikram07]

could you please give me an example how to use sort predicate for each container .

[clanmjc]

struct FairLess
{
    bool operator()(const Adjacent &m, const Adjacent &n){
           return m.fare1 < n.fare1;
    }
};

struct DistanceLess
{
    bool operator()(const Adjacent &m, const Adjacent &n){
           return m.distance1 < n.distance1;
    }
};


queue<Adjacent> myQueue;
std::sort(myQueue.begin(),myQueue.end(),FairLess); //Sorted by fair 

Did not compile any of this code

[kbw]

#include <algorithm>
#include <vector>
#include <string>
#include <ostream>
#include <iostream>

struct Rec
{
	Rec(const std::string &name, int id) : name(name), id(id) {}

	std::string name;
	int id;
};

std::ostream& operator<<(std::ostream &os, const Rec &rec)
{
	os << rec.name << ' ' << rec.id;
	return os;
}

typedef std::vector<Rec> RecV;

bool SortByName(const Rec &a, const Rec &b)
{
	return a.name < b.name;
}

bool SortById(const Rec &a, const Rec &b)
{
	return a.id < b.id;
}

int main()
{
	RecV recs;
	recs.push_back(Rec("Nadine", 4));
	recs.push_back(Rec("Donnet", 2));
	recs.push_back(Rec("Ray", 3));
	recs.push_back(Rec("Dane", 7));

	std::sort(recs.begin(), recs.end(), SortByName);
	std::cout << "Sort by name" << std::endl;
	for (RecV::const_iterator p = recs.begin();  p != recs.end(); ++p)
		std::cout << *p << std::endl;

	std::sort(recs.begin(), recs.end(), SortById);
	std::cout << "Sort by id" << std::endl;
	for (RecV::const_iterator p = recs.begin();  p != recs.end(); ++p)
		std::cout << *p << std::endl;

	return 0;
}

[bikram07]

Great HELP Folks !!!

I tried second approach it worked smoothly ... Thanks a ton .. I am done with the assignment :)


With the first one I was facing error..like Fairless not declared in this scope while passing in sort method.

....

[bikram07]

Could any one please post some link where I can read about the functionality of the same . !

I just used it but not clear how it is working.