Question

this is probably a useless problem but it stuck on my mind for few hours.

I wanna write a function which accepts some (POD) arguments, convert them to string and return the concatenation. for example

template<typename A, typename B>
string ToString(A a, B b)
{
    stringstream ss;
    ss << a << b;
    return ss.str();
}

pretty easy, huh?
but it get pretty tough (for me of course) when I wanna write the same function with unknown number of arguments.

is it even possible? any solution?

Answer 1

Almost like the real thing 🙂

#include <iostream>
#include <string>
#include <sstream>
using namespace std;

template<class L,class R>
struct cons_t
{
    const L &l; const R &r;
    cons_t(const L &_l, const R &_r) : l(_l),r(_r) {}
};
template<>
struct cons_t<void,void>{};
typedef cons_t<void,void> cons;

template<class L,class R,class A>
cons_t< cons_t<L,R>, A> operator , (const cons_t<L,R> &l, const A &arg)
{
    return cons_t< cons_t<L,R>, A>(l,arg);
}
void to_stream(stringstream &s, const cons_t<void,void> &) { }
template<typename L, typename R>
void to_stream(stringstream &s, const cons_t<L,R> &c)
{
    to_stream(s, c.l); 
    s << c.r;
}
template<typename L, typename R>
string to_string(const cons_t<L,R> &c)
{
    stringstream ss;
    to_stream(ss,c);
    return ss.str();
}

#define ToString(...) to_string((cons(),__VA_ARGS__))
int main()
{
    cout << ToString(1,2,"Hi There",3.14159);
}