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
Tcl 8.1 Utf(3tcl)