diff options
Diffstat (limited to 'doc/string.n')
-rw-r--r-- | doc/string.n | 98 |
1 files changed, 71 insertions, 27 deletions
diff --git a/doc/string.n b/doc/string.n index 1cbea16..33780ff 100644 --- a/doc/string.n +++ b/doc/string.n @@ -5,8 +5,8 @@ .\" See the file "license.terms" for information on usage and redistribution .\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. .\" -.so man.macros .TH string n 8.1 Tcl "Tcl Built-In Commands" +.so man.macros .BS .\" Note: do not modify the .SH NAME line immediately below! .SH NAME @@ -19,25 +19,22 @@ string \- Manipulate strings Performs one of several string operations, depending on \fIoption\fR. The legal \fIoption\fRs (which may be abbreviated) are: .TP -\fBstring bytelength \fIstring\fR -. -Returns a decimal string giving the number of bytes used to represent -\fIstring\fR in memory. Because UTF\-8 uses one to three bytes to -represent Unicode characters, the byte length will not be the same as -the character length in general. The cases where a script cares about -the byte length are rare. In almost all cases, you should use the -\fBstring length\fR operation (including determining the length of a -Tcl ByteArray object). Refer to the \fBTcl_NumUtfChars\fR manual -entry for more details on the UTF\-8 representation. +\fBstring cat\fR ?\fIstring1\fR? ?\fIstring2...\fR? +.VS 8.6.2 +Concatenate the given \fIstring\fRs just like placing them directly +next to each other and return the resulting compound string. If no +\fIstring\fRs are present, the result is an empty string. .RS .PP -\fICompatibility note:\fR it is likely that this subcommand will be -withdrawn in a future version of Tcl. It is better to use the -\fBencoding convertto\fR command to convert a string to a known -encoding and then apply \fBstring length\fR to that. +This primitive is occasionally handier than juxtaposition of strings +when mixed quoting is wanted, or when the aim is to return the result +of a concatenation without resorting to \fBreturn\fR \fB\-level 0\fR, +and is more efficient than building a list of arguments and using +\fBjoin\fR with an empty join string. .RE +.VE .TP -\fBstring compare\fR ?\fB\-nocase\fR? ?\fB\-length int\fR? \fIstring1 string2\fR +\fBstring compare\fR ?\fB\-nocase\fR? ?\fB\-length\fI length\fR? \fIstring1 string2\fR . Perform a character-by-character comparison of strings \fIstring1\fR and \fIstring2\fR. Returns \-1, 0, or 1, depending on whether @@ -47,7 +44,7 @@ first \fIlength\fR characters are used in the comparison. If \fB\-length\fR is negative, it is ignored. If \fB\-nocase\fR is specified, then the strings are compared in a case-insensitive manner. .TP -\fBstring equal\fR ?\fB\-nocase\fR? ?\fB\-length int\fR? \fIstring1 string2\fR +\fBstring equal\fR ?\fB\-nocase\fR? ?\fB\-length\fI length\fR? \fIstring1 string2\fR . Perform a character-by-character comparison of strings \fIstring1\fR and \fIstring2\fR. Returns 1 if \fIstring1\fR and \fIstring2\fR are @@ -149,7 +146,9 @@ Any Unicode printing character, including space. .IP \fBpunct\fR 12 Any Unicode punctuation character. .IP \fBspace\fR 12 -Any Unicode space character. +Any Unicode whitespace character, mongolian vowel separator +(U+180e), zero width space (U+200b), word joiner (U+2060) or +zero width no-break space (U+feff) (=BOM). .IP \fBtrue\fR 12 Any of the forms allowed to \fBTcl_GetBoolean\fR where the value is true. @@ -198,9 +197,9 @@ will return \fB1\fR. . Returns a decimal string giving the number of characters in \fIstring\fR. Note that this is not necessarily the same as the -number of bytes used to store the string. If the object is a -ByteArray object (such as those returned from reading a binary encoded -channel), then this will return the actual byte length of the object. +number of bytes used to store the string. If the value is a +byte array value (such as those returned from reading a binary encoded +channel), then this will return the actual byte length of the value. .TP \fBstring map\fR ?\fB\-nocase\fR? \fImapping string\fR . @@ -335,22 +334,67 @@ specified using the forms described in \fBSTRING INDICES\fR. . Returns a value equal to \fIstring\fR except that any leading or trailing characters present in the string given by \fIchars\fR are removed. If -\fIchars\fR is not specified then white space is removed (spaces, -tabs, newlines, and carriage returns). +\fIchars\fR is not specified then white space is removed (any character +for which \fBstring is space\fR returns 1, and "\0"). .TP \fBstring trimleft \fIstring\fR ?\fIchars\fR? . Returns a value equal to \fIstring\fR except that any leading characters present in the string given by \fIchars\fR are removed. If -\fIchars\fR is not specified then white space is removed (spaces, -tabs, newlines, and carriage returns). +\fIchars\fR is not specified then white space is removed (any character +for which \fBstring is space\fR returns 1, and "\0"). .TP \fBstring trimright \fIstring\fR ?\fIchars\fR? . Returns a value equal to \fIstring\fR except that any trailing characters present in the string given by \fIchars\fR are removed. If -\fIchars\fR is not specified then white space is removed (spaces, -tabs, newlines, and carriage returns). +\fIchars\fR is not specified then white space is removed (any character +for which \fBstring is space\fR returns 1, and "\0"). +.SS "OBSOLETE SUBCOMMANDS" +.PP +These subcommands are currently supported, but are likely to go away in a +future release as their functionality is either virtually never used or highly +misleading. +.TP +\fBstring bytelength \fIstring\fR +. +Returns a decimal string giving the number of bytes used to represent +\fIstring\fR in memory when encoded as Tcl's internal modified UTF\-8; +Tcl may use other encodings for \fIstring\fR as well, and does not +guarantee to only use a single encoding for a particular \fIstring\fR. +Because UTF\-8 uses a variable number of bytes to represent Unicode +characters, the byte length will not be the same as the character +length in general. The cases where a script cares about the byte +length are rare. +.RS +.PP +In almost all cases, you should use the +\fBstring length\fR operation (including determining the length of a +Tcl byte array value). Refer to the \fBTcl_NumUtfChars\fR manual +entry for more details on the UTF\-8 representation. +.PP +Formally, the \fBstring bytelength\fR operation returns the content of +the \fIlength\fR field of the \fBTcl_Obj\fR structure, after calling +\fBTcl_GetString\fR to ensure that the \fIbytes\fR field is populated. +This is highly unlikely to be useful to Tcl scripts, as Tcl's internal +encoding is not strict UTF\-8, but rather a modified CESU\-8 with a +denormalized NUL (identical to that used in a number of places by +Java's serialization mechanism) to enable basic processing with +non-Unicode-aware C functions. As this representation should only +ever be used by Tcl's implementation, the number of bytes used to +store the representation is of very low value (except to C extension +code, which has direct access for the purpose of memory management, +etc.) +.PP +\fICompatibility note:\fR it is likely that this subcommand will be +withdrawn in a future version of Tcl. It is better to use the +\fBencoding convertto\fR command to convert a string to a known +encoding and then apply \fBstring length\fR to that. +.PP +.CS +\fBstring length\fR [encoding convertto utf-8 $theString] +.CE +.RE .TP \fBstring wordend \fIstring charIndex\fR . |