How do I increment an IP address represented as a string?

c++, ip-address, string

Solution

You can convert the IP address from a string to an integer using `inet_addr`, then, after manipulating it, convert it back to a string with `inet_ntoa`.

See the documentation for these functions for more info on how to use them.

Here's a small function that will do what you want:

// NOTE: only works for IPv4.  Check out inet_pton/inet_ntop for IPv6 support.
char* increment_address(const char* address_string)
{
    // convert the input IP address to an integer
    in_addr_t address = inet_addr(address_string);

    // add one to the value (making sure to get the correct byte orders)
    address = ntohl(address);
    address += 1;
    address = htonl(address);

    // pack the address into the struct inet_ntoa expects
    struct in_addr address_struct;
    address_struct.s_addr = address;

    // convert back to a string
    return inet_ntoa(address_struct);
}

Include `<arpa/inet.h>` on *nix systems, or `<winsock2.h>` on Windows.

Problem

Original source