If (else)

Conditional structure (II)

    (if logical_expression
        do_statement_1
        else_do_statement_2
    )

Examples

(if (= 1 2) "yes" "no")

"no"

(defun test_if_else (input)
    (if (= input 0)
        (progn
            (princ "First, do this.\n")
            (princ "Then, do that.")
            (princ))
        (progn
            (princ "Else, do nothing.")
            (princ))
    )
)

(test_if_else 0)
(test_if_else 1)