RUNE(3)

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 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 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 returned. 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
/src/lib9/utf/rune.c
/src/lib9/utf/utfrune.c

SEE ALSO
utf(7), tcs(1)