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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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INET_ADDR(3P) POSIX Programmer's Manual INET_ADDR(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
inet_addr, inet_ntoa — IPv4 address manipulation
#include <arpa/inet.h>
in_addr_t inet_addr(const char *cp);
char *inet_ntoa(struct in_addr in);
The inet_addr() function shall convert the string pointed to by
cp, in the standard IPv4 dotted decimal notation, to an integer
value suitable for use as an Internet address.
The inet_ntoa() function shall convert the Internet host address
specified by in to a string in the Internet standard dot
notation.
The inet_ntoa() function need not be thread-safe.
All Internet addresses shall be returned in network order (bytes
ordered from left to right).
Values specified using IPv4 dotted decimal notation take one of
the following forms:
a.b.c.d When four parts are specified, each shall be
interpreted as a byte of data and assigned, from left
to right, to the four bytes of an Internet address.
a.b.c When a three-part address is specified, the last part
shall be interpreted as a 16-bit quantity and placed in
the rightmost two bytes of the network address. This
makes the three-part address format convenient for
specifying Class B network addresses as "128.net.host".
a.b When a two-part address is supplied, the last part
shall be interpreted as a 24-bit quantity and placed in
the rightmost three bytes of the network address. This
makes the two-part address format convenient for
specifying Class A network addresses as "net.host".
a When only one part is given, the value shall be stored
directly in the network address without any byte
rearrangement.
All numbers supplied as parts in IPv4 dotted decimal notation may
be decimal, octal, or hexadecimal, as specified in the ISO C
standard (that is, a leading 0x or 0X implies hexadecimal;
otherwise, a leading '0' implies octal; otherwise, the number is
interpreted as decimal).
Upon successful completion, inet_addr() shall return the Internet
address. Otherwise, it shall return (in_addr_t)(-1).
The inet_ntoa() function shall return a pointer to the network
address in Internet standard dot notation.
No errors are defined.
The following sections are informative.
None.
The return value of inet_ntoa() may point to static data that may
be overwritten by subsequent calls to inet_ntoa().
None.
None.
endhostent(3p), endnetent(3p)
The Base Definitions volume of POSIX.1‐2017, arpa_inet.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 INET_ADDR(3P)
Pages that refer to this page: arpa_inet.h(0p), endservent(3p), freeaddrinfo(3p), inet_ntop(3p)
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HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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