diff options
Diffstat (limited to 'doc/Utf.3')
| -rw-r--r-- | doc/Utf.3 | 22 |
1 files changed, 14 insertions, 8 deletions
@@ -63,7 +63,7 @@ const char * const char * \fBTcl_UtfPrev\fR(\fIsrc, start\fR) .sp -Tcl_UniChar +int \fBTcl_UniCharAtIndex\fR(\fIsrc, index\fR) .sp const char * @@ -121,8 +121,8 @@ case-insensitive (1). .SH DESCRIPTION .PP -These routines convert between UTF-8 strings and Tcl_UniChars. A -Tcl_UniChar is a Unicode character represented as an unsigned, fixed-size +These routines convert between UTF-8 strings and Unicode characters. An +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 \fBTCL_UTF_MAX\fR bytes. A multibyte UTF-8 sequence consists of a lead byte followed by some number of trail bytes. @@ -130,9 +130,12 @@ sequence consists of a lead byte followed by some number of trail bytes. \fBTCL_UTF_MAX\fR is the maximum number of bytes that it takes to represent one Unicode character in the UTF-8 representation. .PP -\fBTcl_UniCharToUtf\fR stores the Tcl_UniChar \fIch\fR as a UTF-8 string +\fBTcl_UniCharToUtf\fR stores the character \fIch\fR as a UTF-8 string in starting at \fIbuf\fR. The return value is the number of bytes stored -in \fIbuf\fR. +in \fIbuf\fR. If ch is a high surrogate (range U+D800 - U+DBFF), then +the return value will be 0 and nothing will be stored. If you still +want to produce UTF-8 output for it (even though knowing it's an illegal +code-point on its own), just call \fBTcl_UniCharToUtf\fR again using ch = -1. .PP \fBTcl_UtfToUniChar\fR reads one UTF-8 character starting at \fIsrc\fR and stores it as a Tcl_UniChar in \fI*chPtr\fR. The return value is the @@ -140,6 +143,9 @@ number of bytes read from \fIsrc\fR. 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 +a byte in the range 0x80 - 0x9F, \fBTcl_UtfToUniChar\fR assumes the +cp1252 encoding, stores the corresponding Tcl_UniChar in \fI*chPtr\fR +and returns 1. If the input is otherwise not in proper UTF-8 format, \fBTcl_UtfToUniChar\fR will store the first byte of \fIsrc\fR in \fI*chPtr\fR as a Tcl_UniChar between 0x0000 and 0x00ff and return 1. @@ -200,7 +206,7 @@ of \fIlength\fR bytes is long enough to be decoded by \fBTcl_UtfToUniChar\fR, 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. +full Unicode character has been seen. .PP \fBTcl_NumUtfChars\fR corresponds to \fBstrlen\fR for UTF-8 strings. It returns the number of Tcl_UniChars that are represented by the UTF-8 string @@ -208,12 +214,12 @@ returns the number of Tcl_UniChars that are represented by the UTF-8 string length is negative, all bytes up to the first null byte are used. .PP \fBTcl_UtfFindFirst\fR corresponds to \fBstrchr\fR for UTF-8 strings. It -returns a pointer to the first occurrence of the Tcl_UniChar \fIch\fR +returns a pointer to the first occurrence of the Unicode character \fIch\fR in the null-terminated UTF-8 string \fIsrc\fR. The null terminator is considered part of the UTF-8 string. .PP \fBTcl_UtfFindLast\fR corresponds to \fBstrrchr\fR for UTF-8 strings. It -returns a pointer to the last occurrence of the Tcl_UniChar \fIch\fR +returns a pointer to the last occurrence of the Unicode character \fIch\fR in the null-terminated UTF-8 string \fIsrc\fR. The null terminator is considered part of the UTF-8 string. .PP |