if
(if test_expression then_expression [else_expression])
The if function performs a conditional evaluation.
The function returns the result of the last expression evaluated.
: (if Test 1 2)
2
: (if (= x 1) (setq ret "Yes")(setq ret "No"))
"No"
: (if (/= x 3) (progn (princ "Not equal 3!")(terpri)(setq x 3)))
Not equal 3!
3
progn