Apple IIe - Page 223

Cassette and Disk Storage with the Apple lie 223
Opening and Closing A Random Access File
The following configuration is used to open a random access file:
Configuration
OPEN filename, Lxx [ , Sx , Vx , Dx]
L is known as the length parameter. L is a required parameter
which denotes the length of each random access record . L can
range
from 1 io 32767.
The CLOSE statement is used to close a random access file just as
it is used to close a sequential file.
Reading and Writing to Random Files
The following configuration is used to read from or write to a
random access file .
Configuration
READ filename, Rxx [ , Sx , Vx , Dx]
WRITE filename, Rxx [ , Sx , Yx, Dx]
R is known as the record parameter. R moves the file pointer to
the beginning of the specified record .
The follow_ing program illustrates reading from and writing to a
random file.
10 D$ = CHR$
(4)
20 PRINT D$; " OPEN RANDOM , L20 "
30 PRINT D$: "WRITE RANDOM , R2 "
40 PRINT "RECORD NUMBER TWO "
50 PRINT D$; " WRITE RANDOM , R3 "
60 PRINT "THIS IS RECORD 3"
70 PRINT D$; " WRITE RANDOM , R1 "
80 PRINT " RECORD 1t
90 PRINTD$; " WRITE RANDOM , R4 "
100 PRINT
'' RECORD 4"
110 PRINT D$; " CLOSE
RANDOM "
120
GOTO 180
130 PRINT D$; " OPEN
RANDOM , L20 "
140 PRINT D$; " READ
RANDOM , R "; R