c++11 template

print.cpp

void printf(const char *s)
{
  while (*s)
  {
    if (*s == '%' && *(++s) != '%')
      throw std::runtime_error("invalid format string: missing arguments");
    std::cout << *s++;
  }
}
 
template<typename T, typename... Args>
void printf(const char* s, T value, Args... args)
{
  while (*s)
  {
    if (*s == '%' && *(++s) != '%')
    {
      std::cout << value;
      printf(*s ? ++s : s, args...); // 即便当*s == 0也会产生调用，以检测更多的类型参数。
      return;
    }
    std::cout << *s++;
  }
  throw std::logic_error("extra arguments provided to printf");
}

template_arg_count.cp

template<typename... args>
struct Count{};
template<>
struct count<> {
    static const int value = 0;
};
 
template<typename T, typename... Args>
struct count<T, Args...> { 
    static const int value = 1 + count<Args...>::value;
};