How do I overload the < operator to be able to use class objects with Map container?

[Ch1156]

I'm following the Learncpp site and it has stuff on operator overloading but I cant seem to figure it out for using a class object, I've been trying to figure this out for hours and all the stuff i found on google hasnt really brought me any luck. I created this small program to isolate my incident so its easier to solve.

#include <iostream>#include <map>
#include <string>
#include <iterator>
 
 
using std::string;
using std::cout;
using std::endl;
using std::map;
using std::pair;
 
 
class Character;
 
 
class Item
{
    public:
        Item(const string& name): m_name(name)
        {}
         
        string GetItemName() const { return m_name; }
         
        friend bool operator< (const Item& a, const Character& b)
        {
            using pair = std::pair< const string, int >;
            return pair{ a.GetItemName(), a.GetItemName() } < pair { b.GetItemInventoryAmount(), b.GetItemInventoryAmount() };
        }
     
    private:
        string m_name{ "Item" };
};
 
 
class Character
{
    public:
        Character(const string& name): m_name(name)
        {}
         
        void AddItemToInventory(Item& item, int amountToAdd);
        void OpenInventory();
         
        int GetItemInventoryAmount() const { return m_itemInventoryStock; }
     
    private:
        string m_name{ "Character" };
        map<Item, int> m_inventory{};
        int m_itemInventoryStock{ 0 };
};
 
 
void Character::AddItemToInventory(Item& item, int amountToAdd)
{
    m_inventory.insert(std::make_pair(item, amountToAdd));
}
 
 
void Character::OpenInventory()
{
    map<Item, int>::iterator it = m_inventory.begin();
}
 
 
 
 
int main()
{
    Character Link("Link");
     
    Item Rupee("Rupee");
     
     
}

[Ganado]

If you have a map where Item is the key, you need to be able to tell the compiler how to order two Items.

So you need an operator like

        friend bool operator<(const Item& a, const Item& b)
        {
            return a.GetItemName() < b.GetItemName();
        }

[seeplus]

What is the operator< supposed to do?

[Manga]

#include <iostream>

 using namespace std;
 

 class MyClass {
     public:
     int a, b;
     
     bool operator < (MyClass& two) {
         return a < two.b;
     }
 };

 
 

 
 
 
int main()
{
   MyClass one;
   MyClass two;
   
   one.a = 5;
   two.b = 10;
   
   cout << (one < two);
     
     
}

[Ch1156]

Thanks guys!