case.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: @(#) case.n 1.8 96/03/25 20:10:49
'\" 
.so man.macros
.TH case n 7.0 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
case \- Evaluate one of several scripts, depending on a given value
.SH SYNOPSIS
\fBcase\fI string \fR?\fBin\fR? \fIpatList body \fR?\fIpatList body \fR...?
.sp
\fBcase\fI string \fR?\fBin\fR? {\fIpatList body \fR?\fIpatList body \fR...?}
.BE

.SH DESCRIPTION
.PP
\fINote: the \fBcase\fI command is obsolete and is supported only
for backward compatibility.  At some point in the future it may be
removed entirely.  You should use the \fBswitch\fI command instead.\fR
.PP
The \fBcase\fR command matches \fIstring\fR against each of
the \fIpatList\fR arguments in order.
Each \fIpatList\fR argument is a list of one or
more patterns.  If any of these patterns matches \fIstring\fR then
\fBcase\fR evaluates the following \fIbody\fR argument
by passing it recursively to the Tcl interpreter and returns the result
of that evaluation.
Each \fIpatList\fR argument consists of a single
pattern or list of patterns.  Each pattern may contain any of the wild-cards
described under \fBstring match\fR.  If a \fIpatList\fR
argument is \fBdefault\fR, the corresponding body will be evaluated
if no \fIpatList\fR matches \fIstring\fR.  If no \fIpatList\fR argument
matches \fIstring\fR and no default is given, then the \fBcase\fR
command returns an empty string.
.PP
Two syntaxes are provided for the \fIpatList\fR and \fIbody\fR arguments.
The first uses a separate argument for each of the patterns and commands;
this form is convenient if substitutions are desired on some of the
patterns or commands.
The second form places all of the patterns and commands together into
a single argument; the argument must have proper list structure, with
the elements of the list being the patterns and commands.
The second form makes it easy to construct multi-line case commands,
since the braces around the whole list make it unnecessary to include a
backslash at the end of each line.
Since the \fIpatList\fR arguments are in braces in the second form,
no command or variable substitutions are performed on them;  this makes
the behavior of the second form different than the first form in some
cases.

.SH KEYWORDS
case, match, regular expression