string.n

linux系统下的音频通信

'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" SCCS: @(#) string.n 1.9 96/08/26 13:00:14
'\" 
.so man.macros
.TH string n 7.6 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
string \- Manipulate strings
.SH SYNOPSIS
\fBstring \fIoption arg \fR?\fIarg ...?\fR
.BE

.SH DESCRIPTION
.PP
Performs one of several string operations, depending on \fIoption\fR.
The legal \fIoption\fRs (which may be abbreviated) are:
.TP
\fBstring compare \fIstring1 string2\fR
Perform a character-by-character comparison of strings \fIstring1\fR and
\fIstring2\fR in the same way as the C \fBstrcmp\fR procedure.  Return
\-1, 0, or 1, depending on whether \fIstring1\fR is lexicographically
less than, equal to, or greater than \fIstring2\fR.
.TP
\fBstring first \fIstring1 string2\fR
Search \fIstring2\fR for a sequence of characters that exactly match
the characters in \fIstring1\fR.  If found, return the index of the
first character in the first such match within \fIstring2\fR.  If not
found, return \-1.
.TP
\fBstring index \fIstring charIndex\fR
Returns the \fIcharIndex\fR'th character of the \fIstring\fR
argument.  A \fIcharIndex\fR of 0 corresponds to the first
character of the string.
If \fIcharIndex\fR is less than 0 or greater than
or equal to the length of the string then an empty string is
returned.
.TP
\fBstring last \fIstring1 string2\fR
Search \fIstring2\fR for a sequence of characters that exactly match
the characters in \fIstring1\fR.  If found, return the index of the
first character in the last such match within \fIstring2\fR.  If there
is no match, then return \-1.
.TP
\fBstring length \fIstring\fR
Returns a decimal string giving the number of characters in \fIstring\fR.
.TP
\fBstring match \fIpattern\fR \fIstring\fR
See if \fIpattern\fR matches \fIstring\fR; return 1 if it does, 0
if it doesn't.  Matching is done in a fashion similar to that
used by the C-shell.  For the two strings to match, their contents
must be identical except that the following special sequences
may appear in \fIpattern\fR:
.RS
.IP \fB*\fR 10
Matches any sequence of characters in \fIstring\fR,
including a null string.
.IP \fB?\fR 10
Matches any single character in \fIstring\fR.
.IP \fB[\fIchars\fB]\fR 10
Matches any character in the set given by \fIchars\fR.  If a sequence
of the form
\fIx\fB\-\fIy\fR appears in \fIchars\fR, then any character
between \fIx\fR and \fIy\fR, inclusive, will match.
.IP \fB\e\fIx\fR 10
Matches the single character \fIx\fR.  This provides a way of
avoiding the special interpretation of the characters
\fB*?[]\e\fR in \fIpattern\fR.
.RE
.TP
\fBstring range \fIstring first last\fR
Returns a range of consecutive characters from \fIstring\fR, starting
with the character whose index is \fIfirst\fR and ending with the
character whose index is \fIlast\fR. An index of 0 refers to the
first character of the string.  
An index of \fBend\fR (or any
abbreviation of it) refers to the last character of the string.
If \fIfirst\fR is less than zero then it is treated as if it were zero, and
if \fIlast\fR is greater than or equal to the length of the string then
it is treated as if it were \fBend\fR.  If \fIfirst\fR is greater than
\fIlast\fR then an empty string is returned.
.TP
\fBstring tolower \fIstring\fR
Returns a value equal to \fIstring\fR except that all upper case
letters have been converted to lower case.
.TP
\fBstring toupper \fIstring\fR
Returns a value equal to \fIstring\fR except that all lower case
letters have been converted to upper case.
.TP
\fBstring trim \fIstring\fR ?\fIchars\fR?
Returns a value equal to \fIstring\fR except that any leading
or trailing characters from the set given by \fIchars\fR are
removed.
If \fIchars\fR is not specified then white space is removed
(spaces, tabs, newlines, and carriage returns).
.TP
\fBstring trimleft \fIstring\fR ?\fIchars\fR?
Returns a value equal to \fIstring\fR except that any
leading characters from the set given by \fIchars\fR are
removed.
If \fIchars\fR is not specified then white space is removed
(spaces, tabs, newlines, and carriage returns).
.TP
\fBstring trimright \fIstring\fR ?\fIchars\fR?
Returns a value equal to \fIstring\fR except that any
trailing characters from the set given by \fIchars\fR are
removed.
If \fIchars\fR is not specified then white space is removed
(spaces, tabs, newlines, and carriage returns).
.TP
\fBstring wordend \fIstring index\fR
Returns the index of the character just after the last one in the
word containing character \fIindex\fR of \fIstring\fR.
A word is considered to be any contiguous range of alphanumeric
or underscore characters, or any single character other than these.
.TP
\fBstring wordstart \fIstring index\fR
Returns the index of the first character in the
word containing character \fIindex\fR of \fIstring\fR.
A word is considered to be any contiguous range of alphanumeric
or underscore characters, or any single character other than these.

.SH KEYWORDS
case conversion, compare, index, match, pattern, string, word