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.TH concat n 8.3 Tcl "Tcl Built-In Commands"
.so man.macros
.BS
'\" Note: do not modify the .SH NAME line immediately below!
.SH NAME
concat \- Join lists together
.SH SYNOPSIS
\fBconcat\fR ?\fIarg arg ...\fR?
.BE
.SH DESCRIPTION
.PP
This command joins each of its arguments together with spaces after
trimming leading and trailing white-space from each of them. If all of the
arguments are lists, this has the same effect as concatenating them
into a single list.
Arguments that are empty (after trimming) are ignored entirely.
It permits any number of arguments;
if no \fIarg\fRs are supplied, the result is an empty string.
.SH EXAMPLES
Although \fBconcat\fR will concatenate lists, flattening them in the process
(so giving the following interactive session):
.PP
.CS
\fI% \fBconcat\fR a b {c d e} {f {g h}}
\fIa b c d e f {g h}\fR
.CE
.PP
it will also concatenate things that are not lists, as can be seen from this
session:
.PP
.CS
\fI% \fBconcat\fR " a b {c " d " e} f"
\fIa b {c d e} f\fR
.CE
.PP
Note also that the concatenation does not remove spaces from the middle of
values, as can be seen here:
.PP
.CS
\fI% \fBconcat\fR "a b c" { d e f }
\fIa b c d e f\fR
.CE
.PP
(i.e., there are three spaces between each of the \fBa\fR, the \fBb\fR and the
\fBc\fR).
.PP
For \fItrue\fR list concatenation, the \fBlist\fR command should be used with
expansion of each input list:
.PP
.CS
\fI% \fRlist {*}"a b c" {*}{ d e f }
\fIa b c d e f\fR
.CE
.SH "SEE ALSO"
append(n), eval(n), join(n), list(n)
.SH KEYWORDS
concatenate, join, list
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