TCL Training Series - Passing an array as procedure argument

A TCL array is an associative array. i.e. there is an (un-ordered) key-value pair in a TCL array. A simple list of elements as in a perl array or a C array is called a 'list' in TCL. If you want to pass an array, which s essentially a collection of variables, to a procedure in TCL, you can use the command `upvar` as explained earlier. You are passing a name to the procedure and then using it to access the array at the previous level.

proc passArray {argArray} {
upvar $argArray a
puts "$a(Tran), $a(Cap)"
puts [array names a]
}

set arrayA(Tran) "0.1"
set arrayA(Cap) "0.2"

passArray arrayA

You should see the results: `0.1, 0.2` `Cap Tran`

While we are at it, let's see the difference with passing a list. Here we pass a variable to the procedure.

proc passList {argList} {
puts $argList
}

set listA {a b c}
passList $listA