Tcl8.5.18/Tk8.5.18 Documentation > TclCmd > append

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append - Append to variable


append varName ?value value value ...?


Append all of the value arguments to the current value of variable varName. If varName does not exist, it is given a value equal to the concatenation of all the value arguments. The result of this command is the new value stored in variable varName. This command provides an efficient way to build up long variables incrementally. For example, “append a $b” is much more efficient than “set a $a$b” if $a is long.


Building a string of comma-separated numbers piecemeal using a loop.
set var 0
for {set i 1} {$i<=10} {incr i} {
   append var "," $i
puts $var
# Prints 0,1,2,3,4,5,6,7,8,9,10


concat, lappend


append, variable
Copyright © 1995-1997 Roger E. Critchlow Jr. Copyright © 1993 The Regents of the University of California. Copyright © 1994-1996 Sun Microsystems, Inc.