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.TH RUNE 3G
.SH NAME
runetochar, chartorune, runelen, fullrune, utflen, utfrune, utfrrune, utfutf \- rune/UTF conversion
.SH SYNOPSIS
.nf
.B
#include <libc.h>
.B
int runetochar(char *s, Rune *r)
.PP
.B
int chartorune(Rune *r, char *s)
.PP
.B
int runelen(long r)
.PP
.B
int fullrune(char *s, int n)
.PP
.B
int utflen(char *s)
.PP
.B
char* utfrune(char *s, long c)
.PP
.B
char* utfrrune(char *s, long c)
.PP
.B
char* utfutf(char *s1, char *s2)
.fi
.SH DESCRIPTION
These routines convert to and from a
.SM UTF
byte stream and runes.
.PP
.I Runetochar
copies one rune at
.I r
to at most
.B UTFmax
characters starting at
.I s
and returns the number of characters copied.
.BR UTFmax ,
defined as
.B 3
in
.BR <libc.h> ,
is the maximum number of bytes required to represent a rune.
.PP
.I Chartorune
copies at most
.B UTFmax
characters starting at
.I s
to one rune at
.I r
and returns the number of characters copied.
If the characters are not exactly in
.SM UTF
format,
.I chartorune
will convert to 0x80 and return 1.
.PP
.I Runelen
returns the number of characters
required to convert
.I r
into
.SM UTF.
.PP
.I Fullrune
returns 1 if the string
.I s
of length
.I n
is long enough to be decoded by
.I chartorune
and 0 otherwise.
This does not guarantee that the string
contains a legal
.SM UTF
encoding.
This routine is used by programs that
obtain input a character at
a time and need to know when a full rune
has arrived.
.PP
The following routines are analogous to the
corresponding string routines with
.B utf
substituted for
.B str
and
.B rune
substituted for
.BR chr .
.PP
.I Utflen
returns the number of runes that
are represented by the
.SM UTF
string
.IR s .
.PP
.I Utfrune
.RI ( utfrrune )
returns a pointer to the first (last)
occurrence of rune
.I c
in the
.SM UTF
string
.IR s ,
or 0 if
.I c
does not occur in the string.
The NUL character terminating a string is considered to
be part of the string
.IR s .
.PP
.I Utfutf
returns a pointer to the first occurrence of
the
.SM UTF
string
.I s2
as a
.SM UTF
substring of
.IR s1 ,
or 0 if there is none.
If
.I s2
is the null string,
.I utfutf
returns
.IR s1 .
.SH SEE ALSO
.IR utf (5g)
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