inet_ntoa(3p) [centos man page]
INET_ADDR(3P) POSIX Programmer's Manual INET_ADDR(3P) PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond- ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. NAME
inet_addr, inet_ntoa - IPv4 address manipulation SYNOPSIS
#include <arpa/inet.h> in_addr_t inet_addr(const char *cp); char *inet_ntoa(struct in_addr in); DESCRIPTION
The inet_addr() function shall convert the string pointed to by cp, in the standard IPv4 dotted decimal notation, to an integer value suit- able 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 reentrant. A function that is not required to be reentrant is not required to 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). RETURN VALUE
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. ERRORS
No errors are defined. The following sections are informative. EXAMPLES
None. APPLICATION USAGE
The return value of inet_ntoa() may point to static data that may be overwritten by subsequent calls to inet_ntoa(). RATIONALE
None. FUTURE DIRECTIONS
None. SEE ALSO
endhostent(), endnetent(), the Base Definitions volume of IEEE Std 1003.1-2001, <arpa/inet.h> COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 . IEEE
/The Open Group 2003 INET_ADDR(3P)
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inet_addr(3XNET) X/Open Networking Services Library Functions inet_addr(3XNET) NAME
inet_addr, inet_network, inet_makeaddr, inet_lnaof, inet_netof, inet_ntoa - Internet address manipulation SYNOPSIS
cc [ flag ... ] file ... -lxnet [ library ... ] #include <arpa/inet.h> in_addr_t inet_addr(const char *cp); in_addr_t inet_lnaof(struct in_addr in); struct in_addr inet_makeaddr(in_addr_t net, in_addr_t lna); in_addr_t inet_netof(struct in_addr in); in_addr_t inet_network(const char *cp); char *inet_ntoa(struct in_addr in); DESCRIPTION
The inet_addr() function converts the string pointed to by cp, in the Internet standard dot notation, to an integer value suitable for use as an Internet address. The inet_lnaof() function takes an Internet host address specified by in and extracts the local network address part, in host byte order. The inet_makeaddr() function takes the Internet network number specified by net and the local network address specified by lna, both in host byte order, and constructs an Internet address from them. The inet_netof() function takes an Internet host address specified by in and extracts the network number part, in host byte order. The inet_network() function converts the string pointed to by cp, in the Internet standard dot notation, to an integer value suitable for use as an Internet network number. The inet_ntoa() function converts the Internet host address specified by in to a string in the Internet standard dot notation. All Internet addresses are returned in network order (bytes ordered from left to right). Values specified using dot notation take one of the following forms: a.b.c.d 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 address. a.b.c When a three-part address is specified, the last part is 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 is 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 is stored directly in the network address without any byte rearrangement. All numbers supplied as parts in dot notation may be decimal, octal, or hexadecimal, that is, a leading 0x or 0X implies hexadecimal, as specified in the ISO C standard; otherwise, a leading 0 implies octal; otherwise, the number is interpreted as decimal. USAGE
The return value of inet_ntoa() may point to static data that may be overwritten by subsequent calls to inet_ntoa(). RETURN VALUES
Upon successful completion, inet_addr() returns the Internet address. Otherwise, it returns (in_addr_t)(-1). Upon successful completion, inet_network() returns the converted Internet network number. Otherwise, it returns (in_addr_t)(-1). The inet_makeaddr() function returns the constructed Internet address. The inet_lnaof() function returns the local network address part. The inet_netof() function returns the network number. The inet_ntoa() function returns a pointer to the network address in Internet-standard dot notation. ERRORS
No errors are defined. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
endhostent(3XNET), endnetent(3XNET), attributes(5), standards(5) SunOS 5.11 10 Jun 2002 inet_addr(3XNET)