Rewriting ( set<pair<x,y>> ) as a struct - c++

Question

I have to write this:
set<pair<float,int>>foo;
foo.insert(make_pair(a, b));
while (!foo.empty())
{
float dist = foo.begin()->first;
int u = foo.begin()->second;
}
But I want to use my own implementation without adding all the functionality of set/pair.
This is basically what I want pair to do:
struct pair2
{
float first;
int second;
pair2(float arg_first, int arg_second)
{
first = arg_first;
second = arg_second;
}
pair2 make_pair2(float first2, int second2)
{
return (pair2(first2,second2));
}
};
I'm not sure if that's completely correct, but I also have to implement set to work with it:
set<pair>foo; //not set<pair<float,int>>foo; since not templated
foo.insert(make_pair2(a,b));
What's the best way to do this? Should I implement set using a vector? All I need set to have is: empty(), begin(), erase() and insert() which vectors already have.

Answer 1

If I understand correctly, you want to have a pair that is "untemplated". You can type alias, which you can use to rename types to some custom type.
Instead of typing std::pair<float, int> each time, you could call it my_pair.
This is how you can do it in C++11:
#include <iostream>
#include <utility>
#include <set>
using my_pair = std::pair<float, int>;
my_pair make_my_pair(float a, int b) {
return std::make_pair(a, b);
}
int main() {
my_pair a(1.5, 2);
my_pair b = make_my_pair(2.2, 3);
std::cout << a.first << " " << a.second << std::endl;
std::cout << b.first << " " << b.second << std::endl;
std::set<my_pair> foo;
foo.insert(make_my_pair(3.4, 4));
return 0;
}
Be sure to compile with -std=c++11.
If you can't/don't want to use C++11 constructs, you can do this as well:
#include <iostream>
#include <utility>
#include <set>
typedef std::pair<float, int> my_pair;
my_pair make_my_pair(float a, int b) {
return std::make_pair(a, b);
}
int main() {
my_pair a(1.5, 2);
my_pair b = make_my_pair(2.2, 3);
std::cout << a.first << " " << a.second << std::endl;
std::cout << b.first << " " << b.second << std::endl;
std::set<my_pair> foo;
foo.insert(make_my_pair(3.4, 4));
return 0;
}