htons and ntohs Post: 302229619

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Top Forums UNIX for Dummies Questions & Answers htons and ntohs Post 302229619 by jim mcnamara on Wednesday 27th of August 2008 10:28:05 AM

08-27-2008

Registered User

Unless I missed something:
1.network default is big endian
2.those calls translate from the endianness of the box to network default

Assuming you used them correctly, they indicate your system is in network byte order.
It may be that in your unistd.h there is _SC_KERNEL_IS_BIGENDIAN defined. That will tell you what the C compiler thinks about system endianness, anyway.

What OS & platform?

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byteorder

BYTEORDER(3)						   BSD Library Functions Manual 					      BYTEORDER(3)

NAME

     htonl, htons, ntohl, ntohs -- convert values between host and network byte order

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <arpa/inet.h>

     uint32_t
     htonl(uint32_t hostlong);

     uint16_t
     htons(uint16_t hostshort);

     uint32_t
     ntohl(uint32_t netlong);

     uint16_t
     ntohs(uint16_t netshort);

DESCRIPTION

     These routines convert 16 and 32 bit quantities between network byte order and host byte order.  (Network byte order is big endian, or most
     significant byte first.)  On machines which have a byte order which is the same as the network order, routines are defined as null macros.

     These routines are most often used in conjunction with Internet addresses and ports as returned by gethostbyname(3) and getservent(3).

SEE ALSO

     gethostbyname(3), getservent(3)

STANDARDS

     The byteorder functions are expected to conform with IEEE Std POSIX.1-200x (``POSIX.1'').

HISTORY

     The byteorder functions appeared in 4.2BSD.

BUGS

     On the VAX bytes are handled backwards from most everyone else in the world.  This is not expected to be fixed in the near future.

BSD
								   June 4, 1993 							       BSD