Difference between revisions of "File Operations"

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== 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.
 
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.
  

Revision as of 09:43, 2 April 2014

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