Variadic templates

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One of the simplest possible examples is the following implementation of max which isn’t even templated on types.

int maximum(int n)
{
    return n;
}

template<typename... Args>
int maximum(int n, Args... args)
{
    return max(n, maximum(args...));
}

Only slightly more complex is the canonical printf implementation:

void printf(const char *s)
{
  while (*s)
  {
    if (*s == '%' && *(++s) != '%')
      throw "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, args...); // call even when *s == 0 to detect extra arguments
      return;
    }
    std::cout << *s++;
  }
  throw "extra arguments provided to printf";
}

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