File Operations

Introduction

Input and output, whether to or from files, are supported on Flash and RAM devices. The files are accessed either in serial or random order. Currently, only ASCII text files are supported – both printable and non-printable characters.

OPEN

Opens an existing file or creates a new one with the name specified in the string expression. The file name should not exceed 8 characters plus extensions. Acceptable file extensions are:

PRG , DAT , TSK , CMP for permanent files on the Flash disk

REC for temporary files on the RAM disk

You can open a text file to read, write or append to the existing file according to mode flag.

“r” - open text file for reading

“w” - truncate to zero length or create text file for writing

“a” - append; open or create text file for writing at end-of-file

Use APPEND to add new lines at the end of the original contents of the file.Use WRITE to overwrite the previous file or to create a new file.

OPEN #, INPUT #, CLOSE, LOC

See serial port.

TELL

Returns current file pointer, offset from the beginning of the file. Value has meaning only for SEEK to move the file pointer within a file.

SEEK

Moves file pointer to specified location. Use with TELL.

File operations example:

program
dim pos as long
dim d1 as double
dim s1 as string

'create file for writing
Open "test.prg" mode ="w" as #1
print #1, "1.2345"
close #1

'append to existing file
Open "test.prg" mode ="a" as #1
print #1, PI
close #1

'read from file
Open "test.prg" mode ="r" as #1

'how many characters in the file?
print "File contains ";loc(1);" characters"
s1 = input$(#1)

'convert from string to double
d1=val(s1)
?d1

'save current file pointer
pos = tell(#1)
?input$(#1)

'rewind file
seek (#1,pos)
?input$(#1)
close #1

end program

Output:

File contains 31 characters
1.234500000000000e+00
3.141592653590000e+00
3.141592653590000e+0

File Types

A File Specification type indicates that the parameter takes a file name.

The file name may have up to 8 characters in the name with 3 characters in the extension. See the next table: USER files are Read/Load/Writable, the SYSTEM files are not.

Extension	Path	Hidden	Erasable	Read/Load/Write
TXT	RAMDisk	TRUE	FALSE	SYSTEM
TMP	RAMDisk	TRUE	TRUE	SYSTEM
BIN	RAMDisk	TRUE	FALSE	SYSTEM
PRG	FlashDisk	FALSE	TRUE	USER
O	FlashDisk	FALSE	TRUE	USER
DAT	FlashDisk	FALSE	TRUE	USER
SCE	RAMDisk	FALSE	TRUE	USER
CSV	FlashDisk	FALSE	TRUE	USER
ERR	RAMDisk	FALSE	FALSE	USER
CNC	FlashDisk	FALSE	TRUE	USER
LOG	FlashDisk	FALSE	FALSE	USER
CFG	FlashDisk	TRUE	FALSE	USER
SYS	FlashDisk	TRUE	FALSE	SYSTEM
MAP	RAMDisk	TRUE	FALSE	SYSTEM
REC	RAMDisk	FALSE	TRUE	USER
CAM	FlashDisk	FALSE	TRUE	USER
TSK	FlashDisk	FALSE	TRUE	USER
CMP	FlashDisk	FALSE	TRUE	USER
ATC	FlashDisk	TRUE	FALSE	SYSTEM
PRT	RAMDisk	TRUE	TRUE	SYSTEM
LIB	FlashDisk	FALSE	TRUE	USER
MEM	RAMDisk	FALSE	TRUE	USER
BAK	FlashDisk	FALSE	TRUE	USER
PRO	FlashDisk	FALSE	TRUE	USER
SAV	FlashDisk	FALSE	TRUE	SYSTEM
NO EXTENSION	FlashDisk	TRUE	FALSE	SYSTEM