| 1 |
578 |
markom |
'\"
|
| 2 |
|
|
'\" Copyright (c) 1993 The Regents of the University of California.
|
| 3 |
|
|
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
|
| 4 |
|
|
'\"
|
| 5 |
|
|
'\" See the file "license.terms" for information on usage and redistribution
|
| 6 |
|
|
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
| 7 |
|
|
'\"
|
| 8 |
|
|
'\" RCS: @(#) $Id: foreach.n,v 1.1.1.1 2002-01-16 10:25:24 markom Exp $
|
| 9 |
|
|
'\"
|
| 10 |
|
|
.so man.macros
|
| 11 |
|
|
.TH foreach n "" Tcl "Tcl Built-In Commands"
|
| 12 |
|
|
.BS
|
| 13 |
|
|
'\" Note: do not modify the .SH NAME line immediately below!
|
| 14 |
|
|
.SH NAME
|
| 15 |
|
|
foreach \- Iterate over all elements in one or more lists
|
| 16 |
|
|
.SH SYNOPSIS
|
| 17 |
|
|
\fBforeach \fIvarname list body\fR
|
| 18 |
|
|
.br
|
| 19 |
|
|
\fBforeach \fIvarlist1 list1\fR ?\fIvarlist2 list2 ...\fR? \fIbody\fR
|
| 20 |
|
|
.BE
|
| 21 |
|
|
|
| 22 |
|
|
.SH DESCRIPTION
|
| 23 |
|
|
.PP
|
| 24 |
|
|
The \fBforeach\fR command implements a loop where the loop
|
| 25 |
|
|
variable(s) take on values from one or more lists.
|
| 26 |
|
|
In the simplest case there is one loop variable, \fIvarname\fR,
|
| 27 |
|
|
and one list, \fIlist\fR, that is a list of values to assign to \fIvarname\fR.
|
| 28 |
|
|
The \fIbody\fR argument is a Tcl script.
|
| 29 |
|
|
For each element of \fIlist\fR (in order
|
| 30 |
|
|
from first to last), \fBforeach\fR assigns the contents of the
|
| 31 |
|
|
element to \fIvarname\fR as if the \fBlindex\fR command had been used
|
| 32 |
|
|
to extract the element, then calls the Tcl interpreter to execute
|
| 33 |
|
|
\fIbody\fR.
|
| 34 |
|
|
.PP
|
| 35 |
|
|
In the general case there can be more than one value list
|
| 36 |
|
|
(e.g., \fIlist1\fR and \fIlist2\fR),
|
| 37 |
|
|
and each value list can be associated with a list of loop variables
|
| 38 |
|
|
(e.g., \fIvarlist1\fR and \fIvarlist2\fR).
|
| 39 |
|
|
During each iteration of the loop
|
| 40 |
|
|
the variables of each \fIvarlist\fP are assigned
|
| 41 |
|
|
consecutive values from the corresponding \fIlist\fP.
|
| 42 |
|
|
Values in each \fIlist\fP are used in order from first to last,
|
| 43 |
|
|
and each value is used exactly once.
|
| 44 |
|
|
The total number of loop iterations is large enough to use
|
| 45 |
|
|
up all the values from all the value lists.
|
| 46 |
|
|
If a value list does not contain enough
|
| 47 |
|
|
elements for each of its loop variables in each iteration,
|
| 48 |
|
|
empty values are used for the missing elements.
|
| 49 |
|
|
.PP
|
| 50 |
|
|
The \fBbreak\fR and \fBcontinue\fR statements may be
|
| 51 |
|
|
invoked inside \fIbody\fR, with the same effect as in the \fBfor\fR
|
| 52 |
|
|
command. \fBForeach\fR returns an empty string.
|
| 53 |
|
|
.SH EXAMPLES
|
| 54 |
|
|
.PP
|
| 55 |
|
|
The following loop uses i and j as loop variables to iterate over
|
| 56 |
|
|
pairs of elements of a single list.
|
| 57 |
|
|
.DS
|
| 58 |
|
|
set x {}
|
| 59 |
|
|
foreach {i j} {a b c d e f} {
|
| 60 |
|
|
lappend x $j $i
|
| 61 |
|
|
}
|
| 62 |
|
|
# The value of x is "b a d c f e"
|
| 63 |
|
|
# There are 3 iterations of the loop.
|
| 64 |
|
|
.DE
|
| 65 |
|
|
.PP
|
| 66 |
|
|
The next loop uses i and j to iterate over two lists in parallel.
|
| 67 |
|
|
.DS
|
| 68 |
|
|
set x {}
|
| 69 |
|
|
foreach i {a b c} j {d e f g} {
|
| 70 |
|
|
lappend x $i $j
|
| 71 |
|
|
}
|
| 72 |
|
|
# The value of x is "a d b e c f {} g"
|
| 73 |
|
|
# There are 4 iterations of the loop.
|
| 74 |
|
|
.DE
|
| 75 |
|
|
.PP
|
| 76 |
|
|
The two forms are combined in the following example.
|
| 77 |
|
|
.DS
|
| 78 |
|
|
set x {}
|
| 79 |
|
|
foreach i {a b c} {j k} {d e f g} {
|
| 80 |
|
|
lappend x $i $j $k
|
| 81 |
|
|
}
|
| 82 |
|
|
# The value of x is "a d e b f g c {} {}"
|
| 83 |
|
|
# There are 3 iterations of the loop.
|
| 84 |
|
|
.DE
|
| 85 |
|
|
.SH KEYWORDS
|
| 86 |
|
|
foreach, iteration, list, looping
|
