Radio Shack TRS-80

Chapter
6
IF
you
liked
Chapter
1
through
5,
THEN
you're going
to love
the rest
of this
book!
Because we're really just getting
into the good stuff.
Like IF-THEN
and
GOTO
statements
that let
your Computer make
decisions
and
take . . . er,
executive action. But
first, a few
more
operators
. . .
Relational operators
allow the
Computer
to compare one
value with
another.
There are
only
three
:
1.
Equals, using
the symbol
=
(How'd
you
guess?)
2. Is greater than, using the symbol >
3. Is less than, using the symboK
Combining these three,
we
come up with three more
operators:
4. Is not equal
to, using the symbolo
5. Is
less than
or equal to, using the
symbol<
=
6. Is greater than or equal
to, using the symbol
>
=
By
adding these
six relational
operators
to the four math
operators
we already
know, plus
new
STA TEMENTs, called
IF-THEN, & GOTO, we
create
a powerful
system
of comparing
and calculating
that becomes the central core
of
everything else
that
follows.
The
IF-THEN
statement, combined
with the six
relational operators
above, gives
us
the
action
part of a
system
of
logic.
Enter and
RUN
this
program:
10 A
=
5
20 IF
A
=
5 THEN 50
30 PRINT
"A DOES NOT
EQUAL
5."
40 END
50 PRINT
"A
EQUALS
5-"
The
screen
should display:
A
EQUALS
5.
THEV
GOTTA
MAKE IT
A MOVIE/"
'''
'
- :
"'.:\'
:
.\l:'-'.v.:\\
"i
R&ample: A<
B
means
A
is
less
tnte B.
Toheh> ;
/'you distinguish
betw«en<
and
>y
just
remember
'
:''.
that
the smaller part
of
the<synibal points
ito
ttte:
smaller
of the two quantities being compared.
29