In most programming languages they work with arrays. In AutoLISP there are no arrays. But you have lists in AutoLISP.
In fact. Lists can perform the same function as arrays. To learn more about it, take a look at my blog. I have written about it.
But let's talk about lists. There are lists functions. There are 18 list functions. Here is a list of them.
- List
- Append
- Cons
- Atom
- Listp
- Length
- Car
- Cdr
- Caar, Cadr, Cadar, Etc.
- Last
- Member
- Nth
- Reverse
- Assoc
- Subst
- Foreach
- Apply
- Mapcar
LIST
(list <expression>...)
This function makes a list of a loose element or loose elements.
Examples:
|
Function |
Gives
back |
|
|
|
|
(list
'a 'b 'c) |
(A
B C) |
|
(list
'a '(b c) “text”) |
(A
(B C) “text”) |
|
(list
3.9 6.7) |
(3.9
6.7) |
APPEND
(append <expression>...)
This function creates a new list out of two or more lists.
|
Function |
Gives
back |
|
|
|
|
(append
'(a b) '(c d)) |
(A
B C D) |
|
(append
'((a) (b)) '(c)) |
((A)
(B) C) |
CONS
(cons <new> <list>)
A new element is added to the list. The new element can be an atom or a list. It comes at the first place of the list. Examples are:
|
Function |
Gives
back |
|
|
|
|
(cons
'a '(b c d)) |
(A
B C D) |
|
(cons
'(a) '(b c d)) |
((A)
B C D) |
Instead of a new element and a list, this function can also be used with two atoms. Then you will get a dotted pair. Examples:
|
Function |
Gives
back |
|
|
|
|
(cons
2 'a) |
(2
. A) |
|
(cons
8 “0”) |
(8
. “0”) |
ATOM
(atom <item>)
This function gives back nil if the item is a list. If not it gives back T or true.
Examples:
(setq a '(x y z))
(setq b 'a)
|
Function |
Give
back |
|
|
|
|
(atom
'a) |
T |
|
(atom
a) |
nil |
|
(atom
'b) |
T |
|
(atom
b) |
T |
|
(atom
'(a b c)) |
nil |
LISTP
(listp <item>)
This function is the same as the prevision function. Except it gives back T if the item is a list and nil if it is not a list.
|
Function |
Gives
back |
|
|
|
|
(listp
'(a b c)) |
T |
|
(listp
'a) |
nil |
|
(listp
3.434) |
nil |
LENGTH
(length <list>)
This function gives the number of element of a list. Or the length of a list.
|
Function |
Gives
back |
|
|
|
|
(length
'(a b c d)) |
4 |
|
(length
'(a b (c d)) |
3 |
|
(length
'()) |
0 |
CAR
(car <list>)
This function gives back the first element of a list. What is given back can be an atom or a list. If the list is empty, nil is given back.
Examples:
|
Function |
Gives
back |
|
|
|
|
(car
'(a b c)) |
3 |
|
(car
'((a b) c) |
2 |
|
(car
'()) |
nil |
CDR
(cdr <list)
This function gives back the list without the first element. The first element can be an atom or a list.
Examples:
|
Function |
Gives
back |
|
|
|
|
(cdr
'(a b c)) |
(B
C) |
|
(cdr
'((a b) c) |
(C) |
|
(cdr
'()) |
nil |
CAAR, CADR, CADAR, etc.
These functions are a combination of the previous functions. You can combine the functions until four levels.
LAST
(last <list>)
The function gives back the last element of a list. Examples:
|
Function |
Gives
back |
|
|
|
|
(last
'(a b c d)) |
D |
|
(last
'(a b (c d)) |
(C
D) |
MEMBER
(member <expression> <list>)
This function checks if the expression is in the list. If so the list is given back starting with the expression.
|
Function |
Gives
back |
|
|
|
|
(member
'c '(a b c d e)) |
(C
D E) |
|
(member
'z '(a b c d e)) |
nil |
NTH
(nth <list>)
This function gives back the nth number minus 1 of the list. The elements of the list are numbered., The number of the first element is zero.
|
Function |
Gives
back |
|
|
|
|
(nth
3 '(a b c d e)) |
D |
|
(nth
0 '(a b c d e)) |
A |
|
(nth
9 '(a b c d e)) |
nil |
REVERSE
(reverse <list>)
This function turns the order of a list around. Example:
|
Function |
Give
back |
|
|
|
|
(reverse
'(a b c)) |
(C
B A) |
ASSOC
(assoc <item> <list)
This function gives back a part list of a list depending on whether the item has been found in the list.
Examples:
(setq ls '((name box) (width 100) (height 200))
|
Function |
Gives
back |
|
|
|
|
(assoc
'name a) |
(NAME
BOX) |
|
(assoc
'width a) |
(WIDTH
100) |
|
(assoc
'length a) |
nil |
SUBST
(subst <new item> <old item> <list>)
This function looks in a list for an old item and replaces it with the new item. If the anew item can be found.
If the old item is not found, then the original list is given back.
Examples:
(setq dm '(a b (c d) b))
|
Function |
Gives
back |
|
|
|
|
(subst
'qq 'b dm) |
(A
QQ (C D) QQ) |
|
(subst
'qq 'z dm) |
(A
B (C D) B) |
|
(subst
'qq (c d) dm) |
(A
B QQ B) |
|
(subst
'(qq rr) 'c d) dm) |
(A
B (QQ RR) B) |
FOREACH
(foreach <name> <list> <expression>)
This function goes through a list. Every item is given a name and the name is evaluated according to the expression.
The result of the last item and expression is what is given back by the fucntion.
Example:
|
Function |
Gives
back |
|
|
|
|
(foreach
nm '(1 2 3) (* nm 2)) |
6 |
In the example the following calculations have been made:
(* 1 2)
(* 2 2)
(* 2 3)
APPLY
(apply <function> <list>)
With this function elements of a list can be evaluated. Examples:
|
Function |
Gives
back |
|
|
|
|
(apply
'+ '(1 2 3)) |
6 |
|
(apply
'strcat '(“Auto” “LISP”) |
AutoLISP |
MAPCAR
(mapcar <function> <list1>...<listn>)
This function evaluates the function specified with all the lists as arguments. In the lists must be the number of needed arguments.
Example:
(setq a 10 b 20 c 30)
(mapcar '1+ (list a b c))
gives back:
(11 21 31)
That is:
(1+ a)
(1+ b)
(1+ c)
(mapcar '+ (10 20 30) (4 3 2))
gives back:
(14 23 32)
That is:
(+ 10 4)
(+ 20 3)
(+ 30 2)
