关于c ++：重载模板运算符调用单独的类运算符

Overloaded template operator calling separate class operator

我有一个包含其他类的优先级队列的模板类，我需要使用优先级重载器来调用单个类重载器，根据单个类的首选项进行比较(在本例中，它是年龄，在另一个类中，它可能是价格)。

毫无疑问，我已经实现了不正确的运算符重载，所以我会很感谢您的建议。

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#include <iostream>
#include <queue>
#include <string>

using namespace std;

class Animal {
public:
Animal();
Animal(string t, int a);
int get_age()const;
bool operator< ( Animal& b) const;
void display()const;
private:
string type;
double age;
};

void Animal::display() const
{
cout <<"Type:" << type <<" Age:" << age;
}
int Animal::get_age() const
{
return age;
}

Animal::Animal(){}

Animal::Animal(string t, int a)
{
type = t;
age = a;
}

bool Animal::operator< ( Animal& b) const
{
return b.get_age();
}

template<typename T>
class Collection {
public:
Collection();
Collection(string n, string d);
void add_item(const T& c);
private:
priority_queue <T> pets;
string name; // Name of the collection
string description; // Descriptions of the collection
};

template<typename T>
Collection<T>::Collection(){}

template<typename T>
Collection<T>::Collection(string n, string d)
{
name = n;
description = d;
}

template<typename T>
bool operator<(const T& one, const T& two)
{
return one.operator<(two);
}

template<typename T>
void Collection<T>::add_item(const T& c)
{
pets.push(c);
}

int main(){
Animal p1("Dog", 10);
Animal p2("Cat", 5);
Animal p3("Turtle", 24);
Collection<Animal> P("Pets","My Pets");
P.add_item(p1);
P.add_item(p2);
P.add_item(p3);
cout << endl;

return 0;
}

我得到这个错误，我不确定我需要做什么来修复它。我必须将类重载保持为单个变量(animal&b)。

task.cpp: In instantiation of 'bool operator<(const T&, const T&) [with T = Animal]': c:\mingw-4.7.1\bin../lib/gcc/mingw32/4.7.1/include/c++/bits/stl_function.h:237:22: required from 'bool std::less<_Tp>::operator()(const _Tp&, const _Tp&)
const [with _Tp = Animal]'
c:\mingw-4.7.1\bin../lib/gcc/mingw32/4.7.1/include/c++/bits/stl_heap.h:310:4: required from 'void std::__adjust_heap(_RandomAccessIterator,
_Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator > >; _Distance = int; _Tp = Animal; _Compare =
std::less]'
c:\mingw-4.7.1\bin../lib/gcc/mingw32/4.7.1/include/c++/bits/stl_heap.h:442:4: required from 'void std::make_heap(_RandomAccessIterator,
_RandomAccessIterator, _Compare) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator > >; _Compare = std::less]'
c:\mingw-4.7.1\bin../lib/gcc/mingw32/4.7.1/include/c++/bits/stl_queue.h:393:9: required from 'std::priority_queue<_Tp, _Sequence, _Compare>::priority_queue(const _Compare&, const _Sequence&) [with _Tp = Animal; _Sequence = std::vector >; _Compare = std::less]' task.cpp:57:45: required from 'Collection::Collection(std::string, std::string) [with T = Animal;
std::string = std::basic_string]' task.cpp:79:43: required
from here task.cpp:66:30: error: no matching function for call to
'Animal::operator<(const Animal&) const' task.cpp:66:30: note: candidate is: task.cpp:36:6: note: bool Animal::operator<(Animal&) const task.cpp:36:6: note: no known conversion for argument 1 from 'const Animal' to 'Animal&' task.cpp: In function 'bool operator<(const T&, const T&) [with T = Animal]':

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