If and if else condition and nested if or cond in AutoLISP

Hi Friends,in this article i will explain about the if and if else condition and  nested if or cond in AutoLISP.

IF:

This is used to execute some code only if a specified condition is true.

Syntax : 

(if (condition)   (progn   code to be executed if condition is true   ) )

Ex:

(setq i 3) (if (= i 3) (progn (alert (strcat “hi......” (rtos i) ) )

If Else:

This is used to execute some code if the condition is true and another code if the condition is false.

  Syntax :  

(if (condition)   (progn   code to be executed if condition is true   ) (progn code to be executed if condition is not true ) )

Ex:

(setq i 3) (if (= i 3)  (princ 3) (princ 4) )

Output: 3

cond – This is nothing but nest-if in C.This function test conditions until one of them is true.  At that point it exits the function.

    Syntax :

(cond (if (condition)   (progn   code to be executed if condition is true   ) (progn code to be executed if condition is not true ) ) (if (condition)   (progn   code to be executed if condition is true   ) (progn code to be executed if condition is not true ) ) )

Ex:

(setq i 30) (cond (if (< i 10)  (princ i) )   (if (< i 20) (princ i) ) (if (< i 30) (princ i) ) )