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author | William Joye <wjoye@cfa.harvard.edu> | 2016-12-21 22:47:21 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2016-12-21 22:47:21 (GMT) |
commit | 5514e37335c012cc70f5b9aee3cedfe3d57f583f (patch) | |
tree | 4ba7d8aad13735e52f59bdce7ca5ba3151ebd7e3 /tcl8.6/doc/while.n | |
parent | 768f87f613cc9789fcf8073018fa02178c8c91df (diff) | |
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-rw-r--r-- | tcl8.6/doc/while.n | 65 |
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diff --git a/tcl8.6/doc/while.n b/tcl8.6/doc/while.n deleted file mode 100644 index 961260c..0000000 --- a/tcl8.6/doc/while.n +++ /dev/null @@ -1,65 +0,0 @@ -'\" -'\" Copyright (c) 1993 The Regents of the University of California. -'\" Copyright (c) 1994-1997 Sun Microsystems, Inc. -'\" -'\" See the file "license.terms" for information on usage and redistribution -'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. -'\" -.TH while n "" Tcl "Tcl Built-In Commands" -.so man.macros -.BS -'\" Note: do not modify the .SH NAME line immediately below! -.SH NAME -while \- Execute script repeatedly as long as a condition is met -.SH SYNOPSIS -\fBwhile \fItest body\fR -.BE -.SH DESCRIPTION -.PP -The \fBwhile\fR command evaluates \fItest\fR as an expression -(in the same way that \fBexpr\fR evaluates its argument). -The value of the expression must a proper boolean -value; if it is a true value -then \fIbody\fR is executed by passing it to the Tcl interpreter. -Once \fIbody\fR has been executed then \fItest\fR is evaluated -again, and the process repeats until eventually \fItest\fR -evaluates to a false boolean value. \fBContinue\fR -commands may be executed inside \fIbody\fR to terminate the current -iteration of the loop, and \fBbreak\fR -commands may be executed inside \fIbody\fR to cause immediate -termination of the \fBwhile\fR command. The \fBwhile\fR command -always returns an empty string. -.PP -Note: \fItest\fR should almost always be enclosed in braces. If not, -variable substitutions will be made before the \fBwhile\fR -command starts executing, which means that variable changes -made by the loop body will not be considered in the expression. -This is likely to result in an infinite loop. If \fItest\fR is -enclosed in braces, variable substitutions are delayed until the -expression is evaluated (before -each loop iteration), so changes in the variables will be visible. -For an example, try the following script with and without the braces -around \fB$x<10\fR: -.PP -.CS -set x 0 -\fBwhile\fR {$x<10} { - puts "x is $x" - incr x -} -.CE -.SH EXAMPLE -.PP -Read lines from a channel until we get to the end of the stream, and -print them out with a line-number prepended: -.PP -.CS -set lineCount 0 -\fBwhile\fR {[gets $chan line] >= 0} { - puts "[incr lineCount]: $line" -} -.CE -.SH "SEE ALSO" -break(n), continue(n), for(n), foreach(n) -.SH KEYWORDS -boolean, loop, test, while |