Intermec PB51 Fingerprint Developer's Guide (old) - Page 65

Closing a File, Verifying the End of a File With EOF, Counting Data Blocks With LOC, Determining

Page 65 highlights

Chapter 4 - Managing Input and Output 10 OPEN "QFILE" FOR OUTPUT AS #1 20 PRINT #1, "Record A,Record B,Record C" 30 CLOSE #1 40 OPEN "QFILE" FOR INPUT AS #1 50 LINE INPUT #1, A$ 60 PRINT A$ 70 CLOSE #1 RUN The printer returns: Record A,Record B,Record C Closing a File When a file is no longer used, it can be closed using a CLOSE statement containing the same reference number as the corresponding OPEN statement. An END statement also closes all open files. Verifying the End of a File With EOF The EOF function is used in connection with INPUT#, LINE INPUT#, or INPUT$ statements to avoid the "Input past end" error condition. When the EOF function encounters the end of a file, it returns the value -1 (TRUE.) If not, it returns the value 0 (FALSE). The next example shows how to use EOF: 10 DIM A%(10) 20 OPEN "DATA" FOR OUTPUT AS #1 30 FOR I%=1 TO 10 40 PRINT #1, I%*1123 50 NEXT I% 60 CLOSE #1 70 OPEN "DATA" FOR INPUT AS #2 80 I%=0 90 WHILE NOT EOF(2) 100 INPUT #2, A%(I%):PRINT A%(I%) 110 I%=1+1:WEND 120 IF EOF(2) THEN PRINT "End of File" RUN Counting Data Blocks With LOC LOC returns the number of 128-byte blocks that have been read or written since the file was OPENed. This example closes the file "ADDRESSES" when record number 100 has been read from the file: 10 OPEN "ADDRESSES" FOR INPUT AS #1 200 IF LOC(1)=100 THEN CLOSE #1 ..... ..... Determining File Length With LOF The LOF function returns the length in bytes of an OPENed file. Intermec Fingerprint Developer's Guide 49

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Chapter 4 — Managing Input and Output
Intermec Fingerprint Developer’s Guide
49
10
OPEN “QFILE” FOR OUTPUT AS #1
20
PRINT #1, “Record A,Record B,Record C”
30
CLOSE #1
40
OPEN “QFILE” FOR INPUT AS #1
50
LINE INPUT #1, A$
60
PRINT A$
70
CLOSE #1
RUN
The printer returns:
Record A,Record B,Record C
Closing a File
When a file is no longer used, it can be closed using a CLOSE statement containing
the same reference number as the corresponding OPEN statement. An END
statement also closes all open files.
Verifying the End of a File With EOF
The EOF function is used in connection with INPUT#, LINE INPUT#, or INPUT$
statements to avoid the “Input past end” error condition.
When the EOF function encounters the end of a file, it returns the value -1 (TRUE.)
If not, it returns the value 0 (FALSE).
The next example shows how to use EOF:
10
DIM A%(10)
20
OPEN “DATA” FOR OUTPUT AS #1
30
FOR I%=1 TO 10
40
PRINT #1, I%*1123
50
NEXT I%
60
CLOSE #1
70
OPEN “DATA” FOR INPUT AS #2
80
I%=0
90
WHILE NOT EOF(2)
100
INPUT #2, A%(I%):PRINT A%(I%)
110
I%=1+1:WEND
120
IF EOF(2) THEN PRINT “End of File”
RUN
Counting Data Blocks With LOC
LOC returns the number of 128-byte blocks that have been read or written since the
file was OPENed. This example closes the file “ADDRESSES” when record number
100 has been read from the file:
10
OPEN “ADDRESSES” FOR INPUT AS #1
.....
.....
.....
200
IF LOC(1)=100 THEN CLOSE #1
.....
.....
Determining File Length With LOF
The LOF function returns the length in bytes of an OPENed file.