•
•
In
order
to
sort the
file
'phone' into alphabetical order of names
we
must read
It
Into
an Internal
array,
sort
it,
and then create a new
file
which will be
in
alphabetical order
of names.
It
is
never good practice
to
delete a
file
before
its
replacement
is
clearly established and
proven correct
You
should therefore copy the
file
first,
as
security,
uSing
a different
name.
The required processes are
as
follows:
1.
Copy the
file
'phone'
to
'phone_temp'
2.
Read the
file
'phone'
Into
an
array.
3.
Sort the
array.
4.
Pause
to
check that everything
IS
in
order.
5.
Delete
file
'phone:
6.
Create new
file
'phone:
This
is
all
the program needs
to
do but
the
new
file
should be immediately checked using:
COPY
mdv1
phone
TO
sc
r
Any further necessary checks should be carried out then:
DELETE mdv2
phone
COPY
mdv1
phone
TO
mdv2
phone
COPY
mdv1
phone
TO
sc
r -
DELETE
mdv1_phone_temp
The above operations complete the process of substituting a sorted
file
for
the original
unsorted one
in
both master and back-up
files.
In
the following program we Illustrate the passing of complete arrays between main
program and procedure. The data passes
in
both directions.
In
line
40
the
array,
row, holding the numbers 1,2,3
is
passed
to
the procedure, addsix.
The parameter, come, receives the Incoming data and the procedure adds six
to
each
element The array parameter,
send,
at
this point holds the numbers
7,8,9.
These numbers are passed back
to
the main program
to
become the values of
array,
black. The values are printed
to
prove that the data has moved
as
required.
Some
Techniques
SORTING
A
MICRODRIVE
FILE
ARRAY
PARAMETERS
•
MAIN
PROGRAM
[row~back_l_
Screen
Output
PROCEDURE
[ome
---_.
+6
---_.
send~
addsix L
~
100
REMark
Pass
Arrays
110
DIM
row(3)
,back(3)
120
FOR
k = 1
TO
3 : LET
row
(k)
= k
130
addsix
row,
back
140
FOR
k = 1
TO
3 : PRINT I
back(k)
I
150
DEFine
PROCedure
addsix(come,send)
160
FOR
k = 1
TO
3 : LET
send(k)=come(k)+6
170
END
DEFine
789
The following procedure receives an array containing data
to
be sorted. The zero element
will
contain the number of
items.
Note that
it
does not matter whether the array
is
numeric
or string. The principle of coercion
will
change string
to
numeric data
if
necessary.
12/84
Program
Output
99
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