Line 28 The string assigned to HH$ is converted
to
a numerical value
by
the
VAL
function. This numerical value
is
assigned
to
the numeric variable HH. Using the
previous example, HH would have the number
13
assigned
to
it. Without the VAL
function, it would not be possible
to
make this assignment.
Line
38 This statement determines whether it
is
AM
or
PM
and assigns an appropriate
string value
to
A$. The value stored in HH
is
compared
to
the numeric constant
12.
Only a numeric variable can be used
in
this way. The use
of
HH$ would have
produced an error and it was for this reason that the string stored in HH$
was
changed
to
a numeric constant and assigned
to
the numeric variable HH.
Line
48
The hour value is converted from a 24 hour format to a
12
hour format. For
example, hour
13
would be converted correctly
to
1 (PM). In this line,
as
well in the
previous line, the variable must
be
a numeric variable. The statement:
HH$
= HH$ -
12
is
illegal and would produce an error.
Line 58 This line uses the STR$ function
to
convert the numeric value stored
in
HH
back
to
a string which
is
then assigned back
to
the string variable HH$. This will
be
concatenated later with another string. In order to
do
this, a string variable must be
used.
Line 68 This line uses the MID$ function
to
read the two minutes digits from TIME$
and stores this two-character string in the string variable MM$. Note that the minutes
are the 4th and 5th characters in the string:
13:05:00
MID$(TIME$,4,2) returns two characters starting with the 4th from the left.
Line 78 In this line, the string to
be
printed
is
concatenated together from the
variables HH$ (hour), MM$ (minutes), and
A$
(AM or PM). A colon
is
inserted
between the hour and minutes.
Line
88
The message
"THE
TIME
IS"
is
displayed followed by the time.
Here are some examples of TIME$ and the resulting output
of
the program:
TIME$
10:15:12
17:08:55
03:18:43
OUTPUT
THE TIME
IS
10:15
AM
THE TIME
IS
5:08 PM
THE TIME
IS
3:18
AM
Note that a leading zero is not printed for the hour. This leading zero
is
lost when the
VAL function
is
applied.
The function VAL converts a string constant or variable
to
a numeric value. The
following examples illustrate this function:
string
123ABBA
2.3CA987
567.4
VAL
123
2.3
567.4
The leftmost characters, up
to
the first character which cannot be part
of
a number,
are converted to a number. This function
is
useful when it is necessary
to
use a
63
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