#include <stdio.h>
#include <boost/type_traits.hpp>

template<typename T> char* ArgToStr(T t, char *str)
{
    sprintf
    (
        str,
        boost::is_floating_point<T>::value ? "%f" :
        boost::is_integral<T>::value ? "%i" : "s",
        t
    );

    return str;
}

int main()
{
    char buffer[10];

    ArgToStr(1, buffer);
    ArgToStr(0.21, buffer);
}