'\"
'\" Copyright (c) 2022 Eric Taylor.  All rights reserved.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
.TH lseq n 8.7 Tcl "Tcl Built-In Commands"
.so man.macros
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
lseq \- Build a numeric sequence returned as a list
.SH SYNOPSIS
\fBlseq \fIstart \fR?(\fB..\fR|\fBto\fR)? \fIend\fR ??\fBby\fR? \fIstep\fR?

\fBlseq \fIstart \fBcount\fR \fIcount\fR ??\fBby\fR? \fIstep\fR?

\fBlseq \fIcount\fR ?\fBby \fIstep\fR?
.BE
.SH DESCRIPTION
.PP
The \fBlseq\fR command creates a sequence of numeric values using the given
parameters \fIstart\fR, \fIend\fR, and \fIstep\fR.
The \fIoperation\fR argument
.QW \fB..\fR
or
.QW \fBto\fR
defines an inclusive range; if it is omitted, the range is exclusive.
The \fBcount\fR option is used to define a count of the number of elements in
the list.
The \fIstep\fR (which may be preceded by \fBby\fR) is 1 if not provided.
The short form with a
single \fIcount\fR value will create a range from 0 to \fIcount\fR-1 (i.e.,
\fIcount\fR values).
.PP
The numeric arguments, \fIstart\fR, \fIend\fR, \fIstep\fR, and \fIcount\fR,
can also be a valid expression. the \fBlseq\fR command will evaluate the
expression (as if with \fBexpr\fR)
and use the numeric result, or return an error as with any invalid argument
value; a non-numeric expression result will result in an error.

.SH EXAMPLES
.CS
.\"
\fBlseq\fR 3
         \fI\(-> 0 1 2\fR

\fBlseq\fR 3 0
         \fI\(-> 3 2 1 0\fR

\fBlseq\fR 10 .. 1 by -2
         \fI\(-> 10 8 6 4 2\fR

set l [\fBlseq\fR 0 -5]
         \fI\(-> 0 -1 -2 -3 -4 -5\fR

foreach i [\fBlseq\fR [llength $l]] {
    puts l($i)=[lindex $l $i]
}
        \fI\(-> l(0)=0\fR
        \fI\(-> l(1)=-1\fR
        \fI\(-> l(2)=-2\fR
        \fI\(-> l(3)=-3\fR
        \fI\(-> l(4)=-4\fR
        \fI\(-> l(5)=-5\fR

foreach i [\fBlseq\fR {[llength $l]-1} 0] {
    puts l($i)=[lindex $l $i]
}
        \fI\(-> l(5)=-5\fR
        \fI\(-> l(4)=-4\fR
        \fI\(-> l(3)=-3\fR
        \fI\(-> l(2)=-2\fR
        \fI\(-> l(1)=-1\fR
        \fI\(-> l(0)=0\fR

set i 17
         \fI\(-> 17\fR
if {$i in [\fBlseq\fR 0 50]} { # equivalent to: (0 <= $i && $i < 50)
    puts "Ok"
} else {
    puts "outside :("
}
        \fI\(-> Ok\fR

set sqrs [lmap i [\fBlseq\fR 1 10] { expr {$i*$i} }]
        \fI\(-> 1 4 9 16 25 36 49 64 81 100\fR
.\"
.CE
.SH "SEE ALSO"
foreach(n), list(n), lappend(n), lassign(n), ledit(n), lindex(n), linsert(n),
llength(n), lmap(n), lpop(n), lrange(n), lremove(n), lreplace(n),
lreverse(n), lsearch(n), lset(n), lsort(n)
.SH KEYWORDS
element, index, list
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