Radio Shack TRS-80 User Manual page 171

f.
Type
a
line
more
than 70
characters
long?
g.
Misspell
PRINT
or
INPUT
(it
happens!)?
h.
Accidentally
type
a
stray
character
in
the
line,
especially an extra
comma
or semi-
colon?
2. If
the error
is
in a
READ
statement, almost
all
the previous
possibilities
apply,
plus:
a. Is
there
really
a
DATA
statement
for the
computer
to read?
Remember,
it
will
only
read a piece of
DATA
once unless
it is
RESTOREd.
Example
:
10 READ X,Y
,Z
20
DATA
2,5,
ERROR:
There
are
only
two numbers
for
the
Computer
to read.
If
you mean
for
Z
to
be
zero,
you must
say
so.
20
DATA 2,5,0
3. If
the bad
area
is
a
FOR-NEXT
loop,
most
of the previous
possibilities also apply, plus:
b.
Do
you
have a
NEXT
statement to
match
the
FOR?
Example:
10
FOR A=l TO
N
ERROR:
Where's the
NEXT
A?
c.
Do
you
have
all
the requirements for a
loop
—
a
starting point,
an ending
point, a
variable
name, and
a
STEP
size if it's
not 1?
Example:
10
A=l TO
N
ERROR:
Must
have
a
FOR
and
a
NEXT.
d.
Did
you
accidentally
nest 2 loops using the
same
variable
in
both loops?
Example:
10
FOR X=l TO
5
20 FOR X=l TO
3
30
PRINT
X
40
NEXT
X
50
NEXT
X
ERROR:
The
nested loops
must
have
different
variables.
at*
9
'A
WOTErTntie^tetMiHiicamma" intae
first
Hse2#
,
:
fcan
cause a
fuH-bJowft
program
crash, requiring
the
Computer to be
tarried
off,
then
ori
again to clear
the trouble.
:':
Some
of
these
FOR-NEXT
loop
errors
won't
cause actual error messages; instead your program
may wind up
in
endless loops, requiring the Use of
the
'BREAK
key.
169