The list is the basic Tcl data structure. A list is simply an ordered collection of stuff; numbers, words, strings, or other lists. Even commands in Tcl are just lists in which the first list entry is the name of a proc, and subsequent members of the list are the arguments to the proc.
Lists can be created in several ways:
split commandlist command.An individual list member can be accessed with the lindex command.
The brief description of these commands is:
list ?arg1? ?arg2? ... ?argN?split string ?splitChars?string into a list of items
wherever the splitChars occur in the code.
SplitChars defaults to being whitespace.
Note that if there are two or more splitChars then each one will be used individually to
split the string. In other words: split
"1234567" "36" would return the following list:
{12 45 7}.lindex list indexindex'th item from the
list. Note: lists start from 0, not 1, so the
first item is at index 0, the second item is at index 1, and so
on.llength listThe items in list can be iterated through using the foreach command:
foreach varname list bodyforeach command will execute
the body code one time for each list item
in list. On each pass, varname will contain the value of the next list item.In reality, the above form of foreach is the simple form, but the command is
quite powerful. It will allow you to take more than one variable at
a time from the list:
foreach {a b} $listofpairs { ... }.
You can even take a variable at a time from multiple lists! For
example:
foreach a $listOfA b $listOfB { ... }
set x "a b c"
puts "Item at index 2 of the list {$x} is: [lindex $x 2]\n"
set y [split 7/4/1776 "/"]
puts "We celebrate on the [lindex $y 1]'th day of the [lindex $y 0]'th month\n"
set z [list puts "arg 2 is $y" ]
puts "A command resembles: $z\n"
set i 0
foreach j $x {
puts "$j is item number $i in list x"
incr i
}