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UTF(3)			    Library Functions Manual			  UTF(3)

NAME
     runetochar,  chartorune,  runelen, fullrune, utflen, utfrune, utfrrune, ut-
     futf - Unicode Text Format functionality

SYNOPSIS
     #include <utf.h>

     int runetochar(char *cp, Rune *rp);

     int chartorune(Rune *rp, char *cp);

     int runelen(long r);

     int fullrune(char *cp, int n);

     int utflen(char *s);

     int utfbytes(char *s);

     char *utfrune(char *cp, long r);

     char *utfrrune(char *cp, long r);

     char *utfutf(char *big, char *little);

     int utf_snprintf(char *buf, size_t size, char *format, ...);

     int utfcmp(char *s1, char *s2);

     int utfncmp(char *s1, char *s2, int rc);

     char *utfcpy(char *dst, char *src);

     char *utfncpy(char *dst, char *src, int nbytes);

     char *utfcat(char *src, char *append);

     char *utfncat(char *src, char *append, int nbytes);

DESCRIPTION
     The UTF routines are used to pack the Unicode text encoding into a standard
     character stream.	To do that effectively, ASCII characters form the lowest
     127 characters of UTF-8. These characters are interchangeable  between  the
     two  character  sets.  A Rune is a Unicode character, defined in the header
     file utf.h.

     runetochar translates a single Rune to a UTF sequence and returns the  num-
     ber  of bytes produced. chartorune is the inverse of this function, return-
     ing the number of bytes consumed.	runelen returns the number of  bytes  in
     the  encoding of a Rune.  fullrune checks that the first n bytes of the UTF
     string cp contain a complete UTF encoding.

     utflen returns the number of runes in a UTF string.   utbytes  returns  the
     number  of  bytes	in a UTF string.  utfrune returns a pointer to the first
     occurrence of a rune in a UTF string.  utfrrune returns a	pointer  to  the
     last.   utfutf searches for the first occurrence of a UTF string in another
     UTF string.

     utf_snprintf is a prticularly  dumb  implementation  of  snprintf	for  utf
     strings  - it only interprets %%, %s and %d sequences in the format string,
     and does no field width calculation on those.

     utfcmp compares two strings lexicographically, Rune by Rune, and returns  a
     value greater than 0, equal to zero, or less than zero depending on whether
     the  first UTF string is greater than, the same as, or less than the second
     string.  utfncmp does the same comparison as utfcmp, with a  maximum  upper
     bound of rc Runes.

     utfcpy  copies  from  source  to destination, Rune by Rune, and returns its
     destination string. No bounds checking is	done  on  the  number  of  Runes
     copied,  or their individual sizes.  The dst argument is returned.  utfncpy
     copies at most nbytes bytes from source to destination, terminating when  a
     null  Rune  is  found  in the source. If the number of bytes copied is less
     than nbytes, then the destination string is paddedf with null (0) bytes. If
     it is equal to or greater than nbytes, no zero bytes is added.  The dst ar-
     gument is returned.  utfcat appends the UTF  string  append  onto	the  UTF
     string src.  utfncat appends the UTF string append onto the UTF string src,
     bearing in mind that the buffer src is only nbytes long.

IMPLEMENTATION
     This  implementation  of  UTF,  nominally	UTF-8, can encode a null Unicode
     character using a one-byte or a two-byte encoding.  Typically, Plan 9  uses
     a one-byte encoding, whilst Java uses a two-byte encoding.  Plan 9 type en-
     coding  makes  backwards compatibility much easier, and loses nothing - all
     the Java functionality is there, there are no embedded null bytes in a  UTF
     string,  due to the encoding of second and third characters, and ordinary C
     strings are recognised as well, which is not the case in Java.  By default,
     a one byte Null-byte encoding is used.

     UTF-8 is defined in X/Open Company Ltd., "File System Safe UCS  Transforma-
     tion  Format (FSS_UTF)", X/Open Preliminary Specification, Document Number:
     P316, which also appears in ISO/IEC 10646, Annex P.

BUGS
     Undoubtably, these are many, and legion.

AUTHOR
     Written by Alistair Crooks  (agc@amdahl.com,  or  agc@westley.demon.co.uk),
     from  a  draft document written by Rob Pike and Ken Thompson, detailing the
     implementation of UTF in the Plan 9 operating system.

									  UTF(3)

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