Print Page - How to make if run one time each?

Title: How to make if run one time each?
Post by: dexter on December 29, 2013, 05:12:40 AM

just say

Code Select Expand

(setq test 0)
(if (= test 0) (begin (println test) (++ test)) (= test 1) (begin (println test)))

and this output as :

Code Select Expand

> (if (= test 0) (begin (println test) (++ test)) (= test 1) (begin (println test)))
0
1

Is it different to C ?

Cause I thought (if ) only run once, so the output should be one line , a 0

new lisp can not do it ?

Title: Re: How to make if run one time each?
Post by: HPW on December 29, 2013, 07:29:44 AM

Code Select Expand

(silent(setq test 0))
(silent(if (= test 0) (begin (println test) (++ test)) (= test 1) (begin (println test))))

The 1 you see is the return value.

Title: Re: How to make if run one time each?
Post by: dexter on December 30, 2013, 09:29:55 PM

Thanks

I never noticed (silent)

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