Atari 400

In troduction to Atari B AS IC 55
Relational Operators
The follo w in g rela tional operato rs are us ed in Atari BASIC.
<
<=
>
>=
------- ~~ I ess than
------...., .~ l ess than o r eq ual to
------....,~ ~ greate r than
------...., .~ greate r than or eq ual to
-------l.~ eq u a I to
<> ------...., .~ not e qual
A relational opera ti on evaluates to eit her true or false. For
exa mple , if the constant 1.0 was co mp ar ed to the constant 2. 0 to
see whether they we re eq ual, the expr ess ion would eva luate to
false. In Atari BASIC, a va lu e of 1 repr esents a co ndition of true ,
while a va lu e of 0 repr ese nt s fa l se.
The only values r et urn ed by a co mp ari so n in BASIC are 1 (true)
o r 0 (false). Th ese va lu es ca n be used as any other int eger would
be us ed . The following resu l ts are ge nerat ed by the following
re lational expressions.
5>7 ........... 0 (false)
3 = 3 - 1 (true)
2<>2 - 0 (false)
(2=2)*4-4
( 1) 7)+7 -7
The first thr ee exa mpl es are easy enoug h to und ersta nd . In the
fourth example , the relation al ex pr ess ion (2 = 2) is eva lu at ed first
as tru e or 1. This r es ult is then multiplied by 4 with a product of 4
as the result. In the fifth exa mple, the relational expression (1 >
7) eva lu ates as false o r O. This res ult is added to 7, with the res ult
being 7.
Relat ion al ope rations using num e ric opera tio ns are fa irly
s tr a ightforw ard. H owever , relational operatio ns us ing string
values may prov e co nfusing to the first-time co mput er user.