Utf(3) Tcl Library Procedures Utf(3)______________________________________________________________________________NAME
Tcl_UniChar, Tcl_UniCharToUtf, Tcl_UtfToUniChar, Tcl_UniCharToUtfD‐
String, Tcl_UtfToUniCharDString, Tcl_UniCharLen, Tcl_UniCharNcmp,
Tcl_UtfCharComplete, Tcl_NumUtfChars, Tcl_UtfFindFirst, Tcl_UtfFind‐
Last, Tcl_UtfNext, Tcl_UtfPrev, Tcl_UniCharAtIndex, Tcl_UtfAtIndex,
Tcl_UtfBackslash - routines for manipulating UTF-8 strings.
SYNOPSIS
#include <tcl.h>
typedef ... Tcl_UniChar;
int
Tcl_UniCharToUtf(ch, buf)
int
Tcl_UtfToUniChar(src, chPtr)
char *
Tcl_UniCharToUtfDString(uniStr, numChars, dstPtr)
Tcl_UniChar *
Tcl_UtfToUniCharDString(src, len, dstPtr)
int
Tcl_UniCharLen(uniStr)
int
Tcl_UniCharNcmp(uniStr, uniStr, num)
int
Tcl_UtfNcmp(src, src, num)
int
Tcl_UtfNcasecmp(src, src, num)
int
Tcl_UtfCharComplete(src, len)
int
Tcl_NumUtfChars(src, len)
char *
Tcl_UtfFindFirst(src, ch)
char *
Tcl_UtfFindLast(src, ch)
char *
Tcl_UtfNext(src)
char *
Tcl_UtfPrev(src, start)
Tcl_UniChar
Tcl_UniCharAtIndex(src, index)
char *
Tcl_UtfAtIndex(src, index)
int
Tcl_UtfBackslash(src, readPtr, dst)
ARGUMENTS
char *buf (out) Buffer in which the UTF-8 rep‐
resentation of the Tcl_UniChar
is stored. At most
TCL_UTF_MAX bytes are stored
in the buffer.
int ch (in) The Tcl_UniChar to be con‐
verted or examined.
Tcl_UniChar *chPtr (out) Filled with the Tcl_UniChar
represented by the head of the
UTF-8 string.
CONST char *src (in) Pointer to a UTF-8 string.
CONST Tcl_UniChar *uniStr (in) A NULL-terminated Unicode
string.
int len (in) The length of the UTF-8 string
in bytes (not UTF-8 charac‐
ters). If negative, all bytes
up to the first null byte are
used.
int numChars (in) The length of the Unicode
string in characters. Must be
greater than or equal to 0.
Tcl_DString *dstPtr (in/out) A pointer to a previously-ini‐
tialized Tcl_DString.
unsigned long num (in) The number of characters to
compare.
CONST char *start (in) Pointer to the beginning of a
UTF-8 string.
int index (in) The index of a character (not
byte) in the UTF-8 string.
int *readPtr (out) If non-NULL, filled with the
number of bytes in the back‐
slash sequence, including the
backslash character.
char *dst (out) Buffer in which the bytes rep‐
resented by the backslash
sequence are stored. At most
TCL_UTF_MAX bytes are stored
in the buffer.
_________________________________________________________________DESCRIPTION
These routines convert between UTF-8 strings and Tcl_UniChars. A
Tcl_UniChar is a Unicode character represented as an unsigned, fixed-
size quantity. A UTF-8 character is a Unicode character represented as
a varying-length sequence of up to TCL_UTF_MAX bytes. A multibyte
UTF-8 sequence consists of a lead byte followed by some number of trail
bytes.
TCL_UTF_MAX is the maximum number of bytes that it takes to represent
one Unicode character in the UTF-8 representation.
Tcl_UniCharToUtf stores the Tcl_UniChar ch as a UTF-8 string in start‐
ing at buf. The return value is the number of bytes stored in buf.
Tcl_UtfToUniChar reads one UTF-8 character starting at src and stores
it as a Tcl_UniChar in *chPtr. The return value is the number of bytes
read from src.. The caller must ensure that the source buffer is long
enough such that this routine does not run off the end and dereference
non-existent or random memory; if the source buffer is known to be null
terminated, this will not happen. If the input is not in proper UTF-8
format, Tcl_UtfToUniChar will store the first byte of src in *chPtr as
a Tcl_UniChar between 0x0000 and 0x00ff and return 1.
Tcl_UniCharToUtfDString converts the given Unicode string to UTF-8,
storing the result in a previously-initialized Tcl_DString. You must
specify the length of the given Unicode string. The return value is a
pointer to the UTF-8 representation of the Unicode string. Storage for
the return value is appended to the end of the Tcl_DString.
Tcl_UtfToUniCharDString coverts the given UTF-8 string to Unicode,
storing the result in the previously-initialized Tcl_Dstring. you may
either specify the length of the given UTF-8 string or "-1", in which
case Tcl_UtfToUniCharDString uses strlen to calculate the length. The
return value is a pointer to the Unicode representation of the UTF-8
string. Storage for the return value is appended to the end of the
Tcl_DString. The Unicode string is terminated with a Unicode NULL
character.
Tcl_UniCharLen corresponds to strlen for Unicode characters. It
accepts a NULL-terminated Unicode string and returns the number of Uni‐
code characters (not bytes) in that string.
Tcl_UniCharNcmp corresponds to strncmp for Unicode characters. It
accepts two NULL-terminated Unicode strings and the number of charac‐
ters to compare. (Both strings are assumed to be at least len charac‐
ters long.) Tcl_UniCharNcmp compares the two strings character-by-
character according to the Unicode character ordering. It returns an
integer greater than, equal to, or less than 0 if the first string is
greater than, equal to, or less than the second string respectively.
Tcl_UtfNcmp corresponds to strncmp for UTF-8 strings. It accepts two
NULL-terminated UTF-8 strings and the number of characters to compare.
(Both strings are assumed to be at least len characters long.)
Tcl_UtfNcmp compares the two strings character-by-character according
to the Unicode character ordering. It returns an integer greater than,
equal to, or less than 0 if the first string is greater than, equal to,
or less than the second string respectively.
Tcl_UtfNcasecmp corresponds to strncasecmp for UTF-8 strings. It is
similar to Tcl_UtfNcmp except comparisons ignore differences in case
when comparing upper, lower or title case characters.
Tcl_UtfCharComplete returns 1 if the source UTF-8 string src of length
len bytes is long enough to be decoded by Tcl_UtfToUniChar, or 0 other‐
wise. This function does not guarantee that the UTF-8 string is prop‐
erly formed. This routine is used by procedures that are operating on
a byte at a time and need to know if a full Tcl_UniChar has been seen.
Tcl_NumUtfChars corresponds to strlen for UTF-8 strings. It returns
the number of Tcl_UniChars that are represented by the UTF-8 string
src. The length of the source string is len bytes. If the length is
negative, all bytes up to the first NULL byte are used.
Tcl_UtfFindFirst corresponds to strchr for UTF-8 strings. It returns a
pointer to the first occurance of the Tcl_UniChar ch in the NULL-termi‐
nated UTF-8 string src. The NULL terminator is considered part of the
UTF-8 string.
Tcl_UtfFindLast corresponds to strrchr for UTF-8 strings. It returns a
pointer to the last occurance of the Tcl_UniChar ch in the NULL termi‐
nated UTF-8 string src. The NULL terminator is considered part of the
UTF-8 string.
Given src, a pointer to some location in a UTF-8 string, Tcl_UtfNext
returns a pointer to the next UTF-8 character in the string. The call‐
er must not ask for the next character after the last character in the
string.
Given src, a pointer to some location in a UTF-8 string, Tcl_UtfPrev
returns a pointer to the previous UTF-8 character in the string. This
function will not back up to a position before start, the start of the
UTF-8 string. If src was already at start, the return value will be
start.
Tcl_UniCharAtIndex corresponds to a C string array dereference or the
Pascal Ord() function. It returns the Tcl_UniChar represented at the
specified character (not byte) index in the UTF-8 string src. The
source string must contain at least index characters.
Tcl_UtfAtIndex returns a pointer to the specified character (not byte)
index in the UTF-8 string src. The source string must contain at least
index characters. This is equivalent to calling Tcl_UtfNext index
times.
Tcl_UtfBackslash is a utility procedure used by several of the Tcl com‐
mands. It parses a backslash sequence and stores the properly formed
UTF-8 character represented by the backslash sequence in the output
buffer dst. At most TCL_UTF_MAX bytes are stored in the buffer.
Tcl_UtfBackslash modifies *readPtr to contain the number of bytes in
the backslash sequence, including the backslash character. The return
value is the number of bytes stored in the output buffer.
See the Tcl manual entry for information on the valid backslash
sequences. All of the sequences described in the Tcl manual entry are
supported by Tcl_UtfBackslash.
KEYWORDS
utf, unicode, backslash
Tcl 8.1 Utf(3)
