AMSTRAD CPC464, Руководство пользователя

Страница: 80 / 249

These items are represented by the various terms, and enclosed in angle brackets q >. For example,
in various places an expression which yields a numeric result is required, this is represented by :
<numeric expression>
Anything not enclosed by angle brackets is required as given. For example the S T 0 P command
takes the form :
STOP
Where there is an optional part in a definition, the optional part is enclosed in square brackets. For
example, if a numeric expression were to be optional then it would appear:
[<numeric expression>]
If an optional part may be repeated (so may appear any numbe: of times, including none at all) an
asterisk is included after the closing square bracket. For example, a string of digits, requiring at
least one digit, would appear :
<digit>[<digit>]*
Such an expression might be:
34
or 344
or 345678 etc
In many places a list of items separated by commas is used. A short form is used, which is best
illustrated by example, thus :
<list of: <expression> means: <expression>[,<expression>]* or:
<list of: [#]<number> means: [#]<number>[ ,[#]<number>]*
an example of which is:
3,4
or 3,4,4
or 3,4,5,6,7,8 etc
The list may be a single object. If the list contains more than one object, then each additional object
must be preceded by a comma delimiter, since it marks the boundary or limit between items that the
computer must treat separately.
Numbers may be expressed in several forms:
a. <unscaled numbers>
. . . ..are numbers without exponentiation
-
i.e. those with no exponent part.
b. <scaled numbers> are numbers that are ‘raised to tee power’ or ‘scaled’ using the form:
2E4 (2 times 10 to the power of 4, or 2.10
4
)
. . . .
.the exponent part may be either positive, or negative.