AutoLISP Basics

Resources

Basics

Use VLIDE to write and test AutoLISP code.
You Can Open Existing Lisp file by File -> Open File
Windows
Main Code Window : This is where you write and edit your AutoLISP code.
Console/Command Line : This is where you can see output and error messages.
Build Output Window : This shows the results of building or compiling your code.
Trace Window : This is useful for debugging, showing the flow of execution.
You can Use Appload button or Ctrl + F9 to load your lisp code into AutoCAD.
You can add your Lisp file to Startup Suite so that it loads automatically when AutoCAD starts.
You can also run Lisp Code Directly in AutoCAD Command Line

Sample Code

Here is a simple AutoLISP function that prints "Hello, World!" to the command line when you type hello in AutoCAD.
defun defines a new function, c: indicates it's a command, and princ is used to print text.
```
(defun c:hello ()
  (princ "Hello, World!")
)
```

Create Custom Command

Below is an example of a custom command that prompts the user to select two points and then

c:test is the name of the command you will type in AutoCAD to run this function.

(defun c:test ()
    ;define the function

    (setq a (getpoint "\nEnter First Point : "))
    ;get the first point

    (setq b (getpoint "\nEnter Second Point : "))
    ;get the second point

    (command "Line" a b "")
    ;draw the line

        (princ)
        ;clean running

)   ;end defun
(princ)
;clean loading

Function for Calculations

You can also define functions that are not directly callable as commands.

(defun myFunction (x y)
  (+ x y)
)
(princ (myFunction 5 10)) ; This will print 15

Basic Syntax

Comments

Use ; to add comments in your code. Anything after ; on the same line is ignored by AutoLISP.

; This is a comment
(defun c:example ()
  (princ "This is an example function") ; This prints a message
)

Print

Used to display messages in the command line.
```
(Princ "Hello, AutoLISP World!")
```

Message Box

Used to display a message box to the user.
```
(alert "This is a message box!")
```

Data Types

Integers
```
(setq myInteger 10)
```
Real Numbers
```
(setq myReal 10.5)
```
Strings
```
(setq myString "Hello, AutoLISP!")
```

Lists

(setq myList '(1 2 3 4 5))
(princ myList) ; This will print the list

(princ (car myList)) ; This will print the first element of the list
(princ (cdr myList)) ; This will print the rest of the list after the first element
(princ (cadr myList)) ; This will print the second element of the list
(princ (caddr myList)) ; This will print the third element of the list

If Statement

Used for conditional execution of code.

(if (> 10 5)
  (princ "10 is greater than 5")
  (princ "10 is not greater than 5")
)

IF Else Statement

Used for conditional execution with an alternative path.

(setq a (getreal "\nEnter a Number : ")
    b (getreal "\nEnter Second Number : ")
)
(if (> a b)
  (princ "a is greater than b")
  (princ "a is not greater than b")
)

Loops

Repeat Loop

(repeat 5
  (princ "This will print 5 times")
)

While Loop

(setq count 0)
(while (< count 5)
  (princ (strcat "\nCount is: " (itoa count)))
  (setq count (+ count 1))
)

Special Functions

Setq

Used to assign values to variables.

(setq myVariable 10)
(princ myVariable) ; This will print 10

GetPoint

Used to get a point from the user in the drawing area.

(setq userPoint (getpoint "\nSelect a point: "))
(princ userPoint) ; This will print the selected point coordinates

GetReal

Used to get a real number from the user.

(setq userReal (getreal "\nEnter a real number: "))
(princ userReal) ; This will print the entered real number

GetDist

Used to get a distance from the user.

(setq userDistance (getdist "\nEnter a distance: "))
(princ userDistance) ; This will print the entered distance

Polar

Used to calculate a new point based on a starting point, distance, and angle.

(setq startPoint (getpoint "\nSelect a starting point: "))
(setq newPoint (polar startPoint (/ pi 4) 10)) ; 45 degrees, 10 units
(princ newPoint) ; This will print the new point coordinates

Command

Used to execute AutoCAD commands from within AutoLISP.

"" is used to indicate the end of a command sequence, similar to pressing Enter.

(setq a (getpoint "\nEnter First Point : "))
(setq b (getpoint "\nEnter Second Point : "))
(Command "LINE" a b "")

Table Search

Used to search for a value in a list or table.

(tblsearch "value" '("value1" "value2" "value3"))