Provided by: tcl8.6-doc_8.6.14+dfsg-1build1_all 
NAME
Tcl_UniChar, Tcl_UniCharToUtf, Tcl_UtfToUniChar, Tcl_UniCharToUtfDString,
Tcl_UtfToUniCharDString, Tcl_UniCharLen, Tcl_UniCharNcmp, Tcl_UniCharNcasecmp,
Tcl_UniCharCaseMatch, Tcl_UtfNcmp, Tcl_UtfNcasecmp, Tcl_UtfCharComplete, Tcl_NumUtfChars,
Tcl_UtfFindFirst, Tcl_UtfFindLast, 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, uniLength, dsPtr)
Tcl_UniChar *
Tcl_UtfToUniCharDString(src, length, dsPtr)
int
Tcl_UniCharLen(uniStr)
int
Tcl_UniCharNcmp(ucs, uct, numChars)
int
Tcl_UniCharNcasecmp(ucs, uct, numChars)
int
Tcl_UniCharCaseMatch(uniStr, uniPattern, nocase)
int
Tcl_UtfNcmp(cs, ct, numChars)
int
Tcl_UtfNcasecmp(cs, ct, numChars)
int
Tcl_UtfCharComplete(src, length)
int
Tcl_NumUtfChars(src, length)
const char *
Tcl_UtfFindFirst(src, ch)
const char *
Tcl_UtfFindLast(src, ch)
const char *
Tcl_UtfNext(src)
const char *
Tcl_UtfPrev(src, start)
Tcl_UniChar
Tcl_UniCharAtIndex(src, index)
const char *
Tcl_UtfAtIndex(src, index)
int
Tcl_UtfBackslash(src, readPtr, dst)
ARGUMENTS
char *buf (out) Buffer in which the UTF-8 representation of
the Tcl_UniChar is stored. At most
TCL_UTF_MAX bytes are stored in the buffer.
int ch (in) The Unicode character to be converted 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 char *cs (in) Pointer to a UTF-8 string.
const char *ct (in) Pointer to a UTF-8 string.
const Tcl_UniChar *uniStr (in) A null-terminated Unicode string.
const Tcl_UniChar *ucs (in) A null-terminated Unicode string.
const Tcl_UniChar *uct (in) A null-terminated Unicode string.
const Tcl_UniChar *uniPattern (in) A null-terminated Unicode string.
int length (in) The length of the UTF-8 string in bytes (not
UTF-8 characters). If negative, all bytes up
to the first null byte are used.
int uniLength (in) The length of the Unicode string in
characters. Must be greater than or equal to
0.
Tcl_DString *dsPtr (in/out) A pointer to a previously initialized
Tcl_DString.
unsigned long numChars (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 backslash sequence, including the
backslash character.
char *dst (out) Buffer in which the bytes represented by the
backslash sequence are stored. At most
TCL_UTF_MAX bytes are stored in the buffer.
int nocase (in) Specifies whether the match should be done
case-sensitive (0) or case-insensitive (1).
_________________________________________________________________________________________________
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 starting 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 0x80
and 0xFF 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 uniLength, 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 converts the given UTF-8 string to Unicode, storing the result in
the previously initialized Tcl_DString. In the argument length, you may either specify
the length of the given UTF-8 string in bytes 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 Unicode characters (not bytes) in that string.
Tcl_UniCharNcmp and Tcl_UniCharNcasecmp correspond to strncmp and strncasecmp,
respectively, for Unicode characters. They accept two null-terminated Unicode strings and
the number of characters to compare. Both strings are assumed to be at least numChars
characters 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_UniCharNcasecmp is the Unicode case insensitive version.
Tcl_UniCharCaseMatch is the Unicode equivalent to Tcl_StringCaseMatch. It accepts a null-
terminated Unicode string, a Unicode pattern, and a boolean value specifying whether the
match should be case sensitive and returns whether the string matches the pattern.
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
numChars 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 bytes is long
enough to be decoded by Tcl_UtfToUniChar/Tcl_UtfNext, or 0 otherwise. This function does
not guarantee that the UTF-8 string is properly 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 length 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 occurrence of the Tcl_UniChar ch in the null-terminated 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 occurrence of the Tcl_UniChar ch in the null-terminated 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 caller must not ask for the next character
after the last character in the string if the string is not terminated by a null
character. Tcl_UtfCharComplete can be used in that case to make sure enough bytes are
available before calling Tcl_UtfNext.
Tcl_UtfPrev is used to step backward through but not beyond the UTF-8 string that begins
at start. If the UTF-8 string is made up entirely of complete and well-formed characters,
and src points to the lead byte of one of those characters (or to the location one byte
past the end of the string), then repeated calls of Tcl_UtfPrev will return pointers to
the lead bytes of each character in the string, one character at a time, terminating when
it returns start.
When the conditions of completeness and well-formedness may not be satisfied, a more
precise description of the function of Tcl_UtfPrev is necessary. It always returns a
pointer greater than or equal to start; that is, always a pointer to a location in the
string. It always returns a pointer to a byte that begins a character when scanning for
characters beginning from start. When src is greater than start, it always returns a
pointer less than src and greater than or equal to (src - TCL_UTF_MAX). The character
that begins at the returned pointer is the first one that either includes the byte
src[-1], or might include it if the right trail bytes are present at src and greater.
Tcl_UtfPrev never reads the byte src[0] nor the byte start[-1] nor the byte
src[-TCL_UTF_MAX-1].
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.
Behavior is undefined if a negative index is given.
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_UtfToUniChar index times. If a negative index is given, the return pointer
points to the first character in the source string.
Tcl_UtfBackslash is a utility procedure used by several of the Tcl commands. 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