cond {!clause}{*} => {result}{*}
clause ::=(test-form {form}{*)}
test-form---a form.
forms---an implicit progn.
results---the values of the forms in the first clause whose test-form yields true, or the primary value of the test-form if there are no forms in that clause, or else nil if no test-form yields true.
cond allows the execution of forms to be dependent on test-form.
Test-forms are evaluated one at a time in the order in which they are given in the argument list until a test-form is found that evaluates to true.
If there are no forms in that clause, the primary value of the test-form is returned by the cond form. Otherwise, the forms associated with this test-form are evaluated in order, left to right, as an implicit progn, and the values returned by the last form are returned by the cond form.
Once one test-form has yielded true, no additional test-forms are evaluated. If no test-form yields true, nil is returned.
(defun select-options ()
(cond ((= a 1) (setq a 2))
((= a 2) (setq a 3))
((and (= a 3) (floor a 2)))
(t (floor a 3)))) => SELECT-OPTIONS
(setq a 1) => 1
(select-options) => 2
a => 2
(select-options) => 3
a => 3
(select-options) => 1
(setq a 5) => 5
(select-options) => 1, 2
section if [Special Operator] , @xref{case; ccase; ecase} .
Go to the first, previous, next, last section, table of contents.