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A Tcl list holds a sequence of elements, each of which can be a number, a string, or another list.
You can create an empty list with the list command:
set user_codes [list]
You can create a list of things with the list command:
set stuff [list foo bar zot]
or a literal list:
set stuff2 {thing1 thing2 thing3}
[llength] returns the number of elements in the list.
set foo [list 1 2 [list 3 4 5]] ==> 1 2 {3 4 5}
llength $foo ==> 3
lindex returns the nth element of the list. The fist element is 0 (zero), like in C. lindex returns an empty string if the requested element is off the end of the list.
set foo [list 1 2 [list 3 4 5]] ==> 1 2 {3 4 5}
lindex $foo 0 ==> 1
[lsearch] returns the index of the list element that matches the argument or -1 if none match.
set community_colleges [list "caltech" "cmu" "rpi"]
lsearch -exact $community_colleges "caltech" ==> 0
lsearch -exact $community_colleges "harvard" ==> -1
[lrange] returns a subset of the elements in the list:
set foo [list 1 2 [list 3 4 5]] ==> 1 2 {3 4 5}
lrange $foo 1 2 ==> 2 {3 4 5}
[lappend] adds an element(s) to the end of a list:
set foo [list 1 2 [list 3 4 5]] ==> 1 2 {3 4 5}
lappend foo [list 6 7] ==> 1 2 {3 4 5} {6 7}
[linsert] inserts an element or elements in a list before the given element:
set foo [list 1 2 [list 3 4 5]] ==> 1 2 {3 4 5}
linsert $foo 0 0 ==> 0 1 2 {3 4 5} {6 7}
[lreplace] replaces a range of elements in a list with the arguements and returns the new list. The original list is unchanged.
set foo [list 1 2 [list 3 4 5]] ==> 1 2 {3 4 5}
lreplace $foo 3 4 3 4 5 6 7 ==> 0 1 2 3 4 5 6 7
set foo ==> 1 2 {3 4 5} {6 7}
[lsort] sorts the elements of a list:
set my_friends [list "herschel" "schlomo" "mendel"]
set my_sorted_friends [lsort -decreasing $my_friends] ==> schlomo mendel herschel
[concat] will merge two or more lists.
set my_friends [list "herschel" "schlomo" "mendel"]
set my_wifes_friends [list "biff" "christine" "clarissa"]
concat $my_wifes_friends $my_friends ==> biff christine clarissa herschel schlomo mendel
split will break a string into lists at the given character.
set my_ip_address 18.1.2.3 ==> 18.1.2.3
set ip_elements [split $my_ip_address "."] ==> four element list,
with values 18 1 2 3
[join] creates a string of all the list elements. join can have an optional string to put between the list elements:
set data {1 2 3 4 5}
join $data ", "
=> 1, 2, 3, 4, 5
set s [join [list "henry" "the" "eighth"]]
puts s
->henry the eighth
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