http://www.purl.org/tcl/home/man/tcl8.4/TclCmd/join.htm
Join converts a Tcl list into a string. It glues together the elements of a list using a supplied string as element separator. Default is a space. For example:
% join {a b c} " and "
a and b and c
% join {a b c} ""
abc- thanks
RS A typical application is to process a text that consists of several lines:
foreach line [split $input \n] {
# do something with line, produce output
lappend outlines $out
}
set result [join $outlines \n] Another is to flatten out one level of embedded lists:
% join {1 {2 {3 4}} 5}
1 2 {3 4} 5Matrices are a frequent application for nested lists. Here's a simple matrix summer that uses join twice: once for concatenating the rows; then for putting + signs in between so expr has something to parse:
proc matsum matrix {expr [join [join $matrix] +]}Tcl syntax help - Arts and crafts of Tcl-Tk programming - Category Command