Converts an address in its standard text presentation form into
    its numeric binary form, in network byte order.
    Format
      #include  <inet.h>
      int inet_pton  ( int af, const char *src, void *dst );

1  –  Arguments

 af
    Specifies the address family. Valid values are AF_INET for an
    IPv4 address and AF_INET6 for an IPv6 address.
 src
    Points to the address text string to be converted.
 dst
    Points to a buffer that is to contain the numeric address.

2  –  Description

    This function converts a text string to a numeric value in
    network byte order.
    o  If the af parameter is AF_INET, the function accepts a string
       in the standard IPv4 dotted-decimal format:
              ddd.ddd.ddd.ddd
       In this format, ddd is a one- to three-digit decimal number
       between 0 and 255.
    o  If the af parameter is AF_INET6, the function accepts a string
       in the following format:
       x:x:x:x:x:x:x:x
       In this format, x is the hexadecimal value of a 16-bit piece
       of the address.
       IPv6 addresses can contain long strings of zero (0) bits. To
       make it easier to write these addresses, you can use double-
       colon characters (::) one time in an address to represent 1 or
       more 16-bit groups of zeros.
    o  For mixed IPv4 and IPv6 environments, the following format is
       also accepted:
       x:x:x:x:x:x:ddd.ddd.ddd.ddd
       In this format, x is the hexadecimal value of a 16-bit piece
       of the address, and ddd is a one- to three-digit decimal value
       between 0 and 255 that represents the IPv4 address.
    The calling application is responsible for ensuring that the
    buffer referred to by the dst parameter is large enough to hold
    the numeric address. AF_INET addresses require 4 bytes and AF_
    INET6 addresses require 16 bytes.

3  –  Return Values

    1                  Indicates success.
    0                  Indicates that the input string is neither a
                       valid IPv4 dotted-decimal string nor a valid
                       IPv6 address string.
    -1                 Indicates a failure. errno is set to the
                       following value.

4  –  Errors

    EAFNOSUPPORT       The address family specified in the af
                       parameter is unknown.