#Autocad lisp enter number on screen code
Type the code above at the AutoCAD command prompt and hit enter. In fact, you can try this for yourself now. The type function will return the data type of a variable. For example, each element in the lists above is an atom e.g. If a variable has a single indivisible value it is an atom. The following are also examples of lists: ( 5 9 7 2 ) and ( 1.5 2.3 4.9 ). In AutoLisp, that point can be described by a single variable, a list of two elements, the first being the X value and the second being the Y value eg: ( 7 10 ). A point in your drawing is described by the value of the X co-ordinate and the value of the Y co-ordinate. Strings are bits of text and can be up to a maximum length of 100 characters eg: Point 1Ī list is a variable that has more than one element. The last, variable a receives the first value to it from outside the program.Īre numbers ranging between -32768 and +32767 without decimal points eg: 1 The fourth way, as the second, but an AutoCAD command. The third way, as the first BUT the C: tells AutoCAD to treat that function as any other AutoCAD command. The second way, you are saying that the variables you are using are LOCAL variables, which are variables that have value only for that program and while that program is running. The first way, you are saying that all variables you plan to use in the program are GLOBAL, which are variables that do not lose their value after the program ends. Defun encloses the entire program and its closing bracket comes after the main body of the program There are different ways of starting a function for example: In AutoLisp the name of the program or function must be defined in the first statement, which is done by using the command:ĭefun is the first actual command and is followed by the name of the function (or program). Remember to come out of the nest with an equal number of parentheses. As you add parentheses, you're nesting commands become deeper and deeper. In turn, that command can act on another. AutoLisp uses parentheses to nest, allowing you to write a command that acts on (evaluates) another command. All commands are surrounded by parentheses.
Parentheses are vital to writing AutoLisp programs. (prompt "This line will print") This is a commentįrom where the semicolon begins, the remainder of the line is a comment statement. A semicolon does not have to begin the line. Write notes about your program, what you are doing and what the variables are. It is used for documentation and explanation of your program. When you begin a line with a semicolon, anything you write after will be ignored by AutoLisp. Structure your program in such a way that it is easy to understand, by yourself and everyone else. Therefore a variable can store just about anything. In AutoLisp, variables may be a collection of letters or numbers as long as they begin with the letters.Įxample of legal variables are as follows:Īn AutoLisp variable may contain more than one value in a single variable. These are like empty boxes in which to store data, to be used later. Is a pre-defined set of instructions that describes a set of actions that AutoLisp is to perform, divided into three sections:ĭraw out or write out in English what you want your program to do. Use a simple text processor such as Notepad to create and edit your lisp files. Hope this helps you and Good Luck in your Lisping - Kenny Ramage Principles of ProgrammingĪll AutoLisp programs must contain the suffix ".LSP" otherwise AutoCAD will not access them when loading.
You can then lookup the relevant AutoLisp commands for a more detailed explanation. I suggest that you go through this tutorial along with the AutoCAD Programmers Reference Guide.
This tutorial is aimed at the AutoCAD users who would like to start learning AutoLisp.
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