inet_addr(3)inet_addr(3)NAMEinet_addr - Translate an Internet network address string to an Internet
address integer
SYNOPSIS
#include <arpa/inet.h>
in_addr_t inet_addr(
const char *string );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
inet_addr(): XNS4.0, XNS5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Defines an Internet dot-formatted address character string of the form
a.b.c.d, where a, b, c, and d may be expressed as decimal, octal, or
hexadecimal integers in the C idiom.
DESCRIPTION
The inet_addr() function translates a dot-formatted Internet character
address string to an Internet address integer. The Internet address
integer is returned as a network byte-ordered integer.
Values specified using dot notation take on one of the following forms:
When all 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
address. When three parts are specified, the last part is interpreted
as a 16-bit quantity and placed in the rightmost two bytes of the net‐
work address. This format is convenient for specifying Class B network
addresses as 128.net.host. When two parts are specified, the last part
is interpreted as a 24-bit quantity and placed in the rightmost three
bytes of the network address. This format is convenient for specifying
Class A network addresses as net.host. When only one part is speci‐
fied, the value is stored directly in the network address without any
byte rearrangement.
All numbers supplied as parts in dot notation can be decimal, octal, or
hexadecimal, as specified in the ISO C standard. A leading 0x or 0X
implies hexadecimal and a leading 0 implies octal. Otherwise, the num‐
ber is interpreted as decimal.
NOTES
The dot-formatted network-address a.b.c.d is returned as the machine
integer dcba.
RETURN VALUES
Upon successful completion, the inet_addr() function returns an equiva‐
lent network byte-ordered address integer. Otherwise, it returns
(in_addr_t)-1.
ERRORS
Current industry standards for inet_addr() do not define error values.
SEE ALSO
Functions: inet_netof(3), inet_lnaof(3), inet_makeaddr(3), inet_net‐
work(3), inet_ntoa(3)
Standards: standards(5)
Network Programmer's Guide
inet_addr(3)
