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RUNE(2)                       System Calls Manual                      RUNE(2)

NAME
       runetochar,  chartorune,  runelen, runenlen, fullrune, utfecpy, utflen,
       utfnlen, utfrune, utfrrune, utfutf - rune/UTF conversion

SYNOPSIS
       #include <u.h>
       #include <libc.h>

       int    runetochar(char *s, Rune *r)

       int    chartorune(Rune *r, char *s)

       int    runelen(long r)

       int    runenlen(Rune *r, int n)

       int    fullrune(char *s, int n)

       char*  utfecpy(char *s1, char *es1, char *s2)

       int    utflen(char *s)

       int    utfnlen(char *s, long n)

       char*  utfrune(char *s, long c)

       char*  utfrrune(char *s, long c)

       char*  utfutf(char *s1, char *s2)

DESCRIPTION
       These routines convert to and from a UTF byte stream and runes.

       Runetochar copies one rune at r to at most UTFmax bytes starting  at  s
       and  returns  the  number  of  bytes  copied.   UTFmax, defined as 3 in
       <libc.h>, is the maximum number of bytes required to represent a rune.

       Chartorune copies at most UTFmax bytes starting at s to one rune  at  r
       and returns the number of bytes copied.  If the input is not exactly in
       UTF format, chartorune will convert to Runeerror (0xFFFD) and return 1.

       Runelen returns the number of bytes required to convert r into UTF.

       Runenlen  returns  the  number of bytes required to convert the n runes
       pointed to by r into UTF.

       Fullrune returns 1 if the string s of length n is long enough to be de‐
       coded by chartorune and 0 otherwise.  This does not guarantee that  the
       string contains a legal UTF encoding.  This routine is used by programs
       that  obtain  input  a byte at a time and need to know when a full rune
       has arrived.

       The following routines are analogous to the corresponding  string  rou‐
       tines with utf substituted for str and rune substituted for chr.

       Utfecpy copies UTF sequences until a null sequence has been copied, but
       writes  no  sequences  beyond  es1.  If any sequences are copied, s1 is
       terminated by a null sequence, and a pointer to that  sequence  is  re‐
       turned.  Otherwise, the original s1 is returned.

       Utflen  returns  the  number  of  runes that are represented by the UTF
       string s.

       Utfnlen returns the number of complete runes that  are  represented  by
       the first n bytes of UTF string s.  If the last few bytes of the string
       contain  an  incompletely  coded  rune, utfnlen will not count them; in
       this way, it differs from utflen, which  includes  every  byte  of  the
       string.

       Utfrune  (utfrrune) returns a pointer to the first (last) occurrence of
       rune c in the UTF string s, or 0 if c does not  occur  in  the  string.
       The  NUL  byte  terminating  a  string  is considered to be part of the
       string s.

       Utfutf returns a pointer to the first occurrence of the UTF  string  s2
       as  a  UTF  substring  of s1, or 0 if there is none.  If s2 is the null
       string, utfutf returns s1.

SOURCE
       /sys/src/libc/port/rune.c
       /sys/src/libc/port/utfrune.c

SEE ALSO
       utf(6), tcs(1)

                                                                       RUNE(2)