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'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\" Copyright (c) 2001 Kevin B. Kenny <kennykb@acm.org>. 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 lreplace n 7.4 Tcl "Tcl Built-In Commands"
.so man.macros
.BS
'\" Note: do not modify the .SH NAME line immediately below!
.SH NAME
lreplace \- Replace elements in a list with new elements
.SH SYNOPSIS
\fBlreplace \fIlist first last \fR?\fIelement element ...\fR?
.BE
.SH DESCRIPTION
.PP
\fBlreplace\fR returns a new list formed by replacing one or more elements of
\fIlist\fR with the \fIelement\fR arguments.
\fIfirst\fR and \fIlast\fR are index values specifying the first and
last elements of the range to replace.
The index values \fIfirst\fR and \fIlast\fR are interpreted
the same as index values for the command \fBstring index\fR,
supporting simple index arithmetic and indices relative to the
end of the list.
0 refers to the first element of the
list, and \fBend\fR refers to the last element of the list.
If \fIlist\fR is empty, then \fIfirst\fR and \fIlast\fR are ignored.
.PP
If \fIfirst\fR is less than zero, it is considered to refer to before the
first element of the list.
.VS TIP505
If \fIfirst\fR indicates a position greater than the index of the last element
of the list, it is treated as if it is an index one greater than the last
element. This allows this command to append elements to the list.
.VE TIP505
For non-empty lists, the element indicated
by \fIfirst\fR must exist, or \fIfirst\fR must indicate before the
start of the list.
.PP
If \fIlast\fR is less than \fIfirst\fR, then any specified elements
will be inserted into the list before the point specified by \fIfirst\fR
with no elements being deleted.
.VS TIP505
If \fIlast\fR is greater than the index of the last item of the list, it is
treated as if it is an index one greater than the last element. This means
that if it is also greater than than \fIfirst\fR, all elements from
\fIfirst\fR to the end of the list will be replaced, and otherwise the
elements will be appended.
.VE TIP505
.PP
The \fIelement\fR arguments specify zero or more new arguments to
be added to the list in place of those that were deleted.
Each \fIelement\fR argument will become a separate element of
the list. If no \fIelement\fR arguments are specified, then the elements
between \fIfirst\fR and \fIlast\fR are simply deleted. If \fIlist\fR
is empty, any \fIelement\fR arguments are added to the end of the list.
.SH EXAMPLES
.PP
Replacing an element of a list with another:
.PP
.CS
% \fBlreplace\fR {a b c d e} 1 1 foo
a foo c d e
.CE
.PP
Replacing two elements of a list with three:
.PP
.CS
% \fBlreplace\fR {a b c d e} 1 2 three more elements
a three more elements d e
.CE
.PP
Deleting the last element from a list in a variable:
.PP
.CS
% set var {a b c d e}
a b c d e
% set var [\fBlreplace\fR $var end end]
a b c d
.CE
.PP
A procedure to delete a given element from a list:
.PP
.CS
proc lremove {listVariable value} {
upvar 1 $listVariable var
set idx [lsearch -exact $var $value]
set var [\fBlreplace\fR $var $idx $idx]
}
.CE
.PP
.VS TIP505
Adding elements to the end of the list; note that \fBend+2\fR will initially
be treated as if it is \fB6\fR here, but both that and \fB12345\fR are greater
than the index of the final item so they behave identically:
.PP
.CS
% set var {a b c d e}
a b c d e
% set var [\fBlreplace\fR $var 12345 end+2 f g h i]
a b c d e f g h i
.CE
.VE TIP505
.SH "SEE ALSO"
list(n), lappend(n), lindex(n), linsert(n), llength(n), lsearch(n),
lset(n), lrange(n), lsort(n),
string(n)
.SH KEYWORDS
element, list, replace
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