Internet network number manipulation routines
Standard C Library (libc, -lc)
, const void
, const char
() function converts an
Internet network number from network format (usually a
or some other binary form, in
network byte order) to CIDR presentation format (suitable for external display
purposes). The bits
argument is the number of
bits in src
that are the network number. It
if a system error occurs (in
which case, errno
will have been set), or it
returns a pointer to the destination string.
() function converts a
presentation format Internet network number (that is, printable form as held
in a character string) to network format (usually a
or some other internal binary
representation, in network byte order). It returns the number of bits (either
computed based on the class, or specified with /CIDR), or -1 if a failure
occurred (in which case errno
will have been
set. It will be set to
Internet network number was not valid).
The currently supported values for af
argument is the size of the result
Internet network numbers may be specified in one of the following forms:
When four parts are specified, each is interpreted as a byte of data and
assigned, from left to right, to the four bytes of an Internet network number.
Note that when an Internet network number is viewed as a 32-bit integer
quantity on a system that uses little-endian byte order (such as the Intel
386, 486, and Pentium processors) the bytes referred to above appear as
”. That is, little-endian bytes
are ordered from right to left.
When a three part number is specified, the last part is interpreted as a 16-bit
quantity and placed in the rightmost two bytes of the Internet network number.
This makes the three part number format convenient for specifying Class B
network numbers as “
When a two part number is supplied, the last part is interpreted as a 24-bit
quantity and placed in the rightmost three bytes of the Internet network
number. This makes the two part number format convenient for specifying Class
A network numbers as “
When only one part is given, the value is stored directly in the Internet
network number without any byte rearrangement.
All numbers supplied as “parts” in a
’ notation may be decimal, octal, or
hexadecimal, as specified in the C language (i.e., a leading 0x or 0X implies
hexadecimal; otherwise, a leading 0 implies octal; otherwise, the number is
interpreted as decimal).
() functions appeared in BIND