RUNE(2) 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 4 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.
Page 1 Plan 9 (printed 11/24/24)
RUNE(2) RUNE(2)
Fullrune returns 1 if the string s of length n is long
enough to be decoded 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 routines with utf substituted for str and rune sub-
stituted 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 returned. Otherwise, the origi-
nal 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 repre-
sented 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/utfecpy.c
/sys/src/libc/port/utfrune.c
/sys/src/libc/port/utfrrune.c
/sys/src/libc/port/utflen.c
/sys/src/libc/port/utfnlen.c
/sys/src/libc/port/utfutf.c
SEE ALSO
utf(6), tcs(1)
BUGS
When re-encoding UTF strings with chartorune and runetochar
one has to consider that encoding a Runeerror (0xFFFD) that
resulted from invalid encoded input can yield a longer UTF
sequence on the output.
Page 2 Plan 9 (printed 11/24/24)