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scanning section Tcl Commands, version 9.0.4 ...........................................................................lseq: DESCRIPTION: output-directive: unexpected .CS format: \# increasing: % <b>lseq</b> 1 to 5 ....
134 lines
3.3 KiB
Plaintext
134 lines
3.3 KiB
Plaintext
'\"
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'\" Copyright (c) 2022 Eric Taylor. All rights reserved.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH lseq n 9.0 Tcl "Tcl Built-In Commands"
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.so man.macros
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.BS
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'\" Note: do not modify the .SH NAME line immediately below!
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.SH NAME
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lseq \- Build a numeric sequence returned as a list
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.SH SYNOPSIS
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.nf
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\fBlseq \fIstart \fR?(\fB..\fR|\fBto\fR)? \fIend\fR ??\fBby\fR? \fIstep\fR?
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\fBlseq \fIstart \fBcount\fI count\fR ??\fBby\fR? \fIstep\fR?
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\fBlseq \fIcount\fR ?\fBby \fIstep\fR?
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.fi
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.BE
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.SH DESCRIPTION
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.PP
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The \fBlseq\fR command creates a sequence of numeric values, which may
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be either wide integers or doubles, using the given
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parameters \fIstart\fR, \fIend\fR, and \fIstep\fR. The \fIoperation\fR
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argument "\fB..\fR" or "\fBto\fR" defines the range. The "\fBcount\fR" option
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is used to define a count of the number of elements in the list. A short form
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use of the command, with a single count value, will create a range from 0 to
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\fIcount\fR-1.
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.PP
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The \fBlseq\fR command can produce both increasing and decreasing
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sequences. When both \fIstart\fR and \fIend\fR are provided without a
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\fIstep\fR value, then if \fIstart\fR <= \fIend\fR, the sequence will be
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increasing and if \fIstart\fR > \fIend\fR it will be decreasing. If a
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\fIstep\fR value is included, it's sign should agree with the direction of the
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sequence (descending \(-> negative and ascending \(-> positive), otherwise the
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list will have a length of 0. For example:
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.RS
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.PP
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.CS \"
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# increasing:
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% \fBlseq\fR 1 to 5
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\fI\(-> 1 2 3 4 5\fR
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# decreasing:
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% \fBlseq\fR 5 to 1
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\fI\(-> 5 4 3 2 1\fR
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# doubles:
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% \fBlseq\fR 0 0.5 by 0.1
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\fI\(-> 0.0 0.1 0.2 0.3 0.4 0.5\fR
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# decreasing, step with wrong sign:
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% \fBlseq\fR 6 to 1 by 2
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\fI\(-> {}\fR
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# step of 0,
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% \fBlseq\fR 3 to 9 by 0
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\fI\(-> 3\fR
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.\"
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.CE
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.RE
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.PP
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\fIStart\fR defines the initial value and \fIend\fR defines the limit, not
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necessarily the last value. \fBlseq\fR produces a list with \fIcount\fR
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elements, always, even if the step value is 0. and if \fIcount\fR is not
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supplied, it is computed as:
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.RS
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.PP
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.CS
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\fIcount\fR = int( ( (\fIend\fR - \fIstart\fR) / \fIstep\fR ) + 1 )
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.CE
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.RE
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.SH EXAMPLES
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.CS
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.\"
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\fBlseq\fR 3
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\fI\(-> 0 1 2\fR
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\fBlseq\fR 3 0
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\fI\(-> 3 2 1 0\fR
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\fBlseq\fR 10 .. 1 by -2
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\fI\(-> 10 8 6 4 2\fR
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set l [\fBlseq\fR 0 -5]
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\fI\(-> 0 -1 -2 -3 -4 -5\fR
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\fBlseq\fR 1 count 5 by 0
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\fI\(-> 1 1 1 1 1\fR
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foreach i [\fBlseq\fR [llength $l]] {
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puts l($i)=[lindex $l $i]
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}
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\fI\(-> l(0)=0\fR
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\fI\(-> l(1)=-1\fR
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\fI\(-> l(2)=-2\fR
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\fI\(-> l(3)=-3\fR
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\fI\(-> l(4)=-4\fR
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\fI\(-> l(5)=-5\fR
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foreach i [\fBlseq\fR {[llength $l]-1} 0] {
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puts l($i)=[lindex $l $i]
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}
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\fI\(-> l(5)=-5\fR
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\fI\(-> l(4)=-4\fR
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\fI\(-> l(3)=-3\fR
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\fI\(-> l(2)=-2\fR
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\fI\(-> l(1)=-1\fR
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\fI\(-> l(0)=0\fR
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set i 17
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\fI\(-> 17\fR
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if {$i in [\fBlseq\fR 0 50]} { # equivalent to: (0 <= $i && $i <= 50)
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puts "Ok"
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} else {
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puts "outside :("
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} \fI\(-> Ok\fR
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set sqrs [lmap i [\fBlseq\fR 1 10] { expr {$i*$i} }]
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\fI\(-> 1 4 9 16 25 36 49 64 81 100\fR
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.\"
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.CE
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.SH "SEE ALSO"
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foreach(n), list(n), lappend(n), lassign(n), lindex(n), linsert(n), llength(n),
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lmap(n), lpop(n), lrange(n), lremove(n), lreplace(n),
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lreverse(n), lsearch(n), lset(n), lsort(n)
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.SH KEYWORDS
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element, index, list
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'\" Local Variables:
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'\" mode: nroff
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'\" fill-column: 78
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'\" End:
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