ref: 4756cf549a8b0e9a6924713666770045b13dd8b8
dir: /sys/man/2/rune/
.TH RUNE 2 .SH NAME runetochar, chartorune, runelen, runenlen, fullrune, utfecpy, utflen, utfnlen, utfrune, utfrrune, utfutf \- rune/UTF conversion .SH SYNOPSIS .ta \w'\fLchar*xx'u .B #include <u.h> .br .B #include <libc.h> .PP .B int runetochar(char *s, Rune *r) .PP .B int chartorune(Rune *r, char *s) .PP .B int runelen(long r) .PP .B int runenlen(Rune *r, int n) .PP .B int fullrune(char *s, int n) .PP .B char* utfecpy(char *s1, char *es1, char *s2) .PP .B int utflen(char *s) .PP .B int utfnlen(char *s, long n) .PP .B char* utfrune(char *s, long c) .PP .B char* utfrrune(char *s, long c) .PP .B char* utfutf(char *s1, char *s2) .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 bytes starting at .I s and returns the number of bytes copied. .BR UTFmax , defined as .B 4 in .BR <libc.h> , is the maximum number of bytes required to represent a rune. .PP .I Chartorune copies at most .B UTFmax bytes starting at .I s to one rune at .I r and returns the number of bytes copied. If the input is not exactly in .SM UTF format, .I chartorune will convert to .B Runeerror (0xFFFD) and return 1. .PP .I Runelen returns the number of bytes required to convert .I r into .SM UTF. .PP .I Runenlen returns the number of bytes required to convert the .I n runes pointed to by .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 byte 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 Utfecpy copies UTF sequences until a null sequence has been copied, but writes no sequences beyond .IR es1 . If any sequences are copied, .I s1 is terminated by a null sequence, and a pointer to that sequence is returned. Otherwise, the original .I s1 is returned. .PP .I Utflen returns the number of runes that are represented by the .SM UTF string .IR s . .PP .I Utfnlen returns the number of complete runes that are represented by the first .I n bytes of .SM UTF string .IR s . If the last few bytes of the string contain an incompletely coded rune, .I utfnlen will not count them; in this way, it differs from .IR utflen , which includes every byte of the string. .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 byte 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 SOURCE .B /sys/src/libc/port/rune.c .br .B /sys/src/libc/port/utfecpy.c .br .B /sys/src/libc/port/utfrune.c .br .B /sys/src/libc/port/utfrrune.c .br .B /sys/src/libc/port/utflen.c .br .B /sys/src/libc/port/utfnlen.c .br .B /sys/src/libc/port/utfutf.c .SH SEE ALSO .IR utf (6), .IR tcs (1) .SH BUGS When re-encoding UTF strings with .I chartorune and .I runetochar one has to consider that encoding a .I Runeerror (0xFFFD) that resulted from invalid encoded input can yield a longer UTF sequence on the output.