The Modern C++ Challenge

16. Enumerating IPv4 addresses in a range

To be able to enumerate IPv4 addresses in a given range, it should first be possible to compare IPv4 values. Therefore, we should implement at least operator<, but the following listing contains implementation for all comparison operators: ==, !=, <, >, <=, and >=. Also, in order to increment an IPv4 value, implementations for both the prefix and postfix operator++ are provided. The following code is an extension of the IPv4 class from the previous problem:

ipv4& operator++(){   *this = ipv4(1 + to_ulong());   return *this;}ipv4& operator++(int){   ipv4 result(*this);   ++(*this);   return *this;}friend bool operator==(ipv4 const & a1, ipv4 const & a2) noexcept{   return a1.data == a2.data;}friend bool operator!=(ipv4 ...