Argox PA-20 Programming Guide - Manual (Page 44)

PT-20 Programming Guide 42
Description： The lseek function moves the file pointer of a DAT file whose
file handle is specified in the argument fd to a new position
within the file. The new position is specified with an offset byte
address to a specific origin. The offset byte address is specified
in the argument offset which is a long integer. There are 3
possible values for the argument origin.
The values and their interpretations are listed below.
Value of origin Interpretation
1 beginning of file
0 current file pointer position
-1 end of file
Returns： When successful, lseek returns the new byte offset address of the
file pointer from the beginning of file. In case of error, lseek
returns a long value of -1L and an error code is set to the global
variable fErrorCode to indicate the error condition encountered.
Possible error codes and their interpretation are listed below.
fErrorCode： 2:File specified by fd does not exist.
9:Illegal offset value.
10:Illegal origin value.
15:New position is beyond end-of-file.
open
Purpose： Open a DAT file and get the file handle of the file for further
processing.
Syntax： int open(char *filename);
Example call： if (fd = open(“C:\\data\\store.dat”)>0)
_puts(“store.dat opened!”);
Includes： #include “SDK.h ”
Description： The open function opens a DAT file specified by filename and
gets the file handle of the file. A file handle is a positive integer
(excludes 0) used to identify the file for subsequent file
manipulations on the file. If the file specified by filename does
not exist, it will be created first. If filename exceeds 8 characters,
it will be truncated to 8 characters long. After the file is opened,
the file pointer points to the beginning
of file.
Returns： If open successfully opens the file, it returns the file handle of the
file being opened. In case of error, open will return an integer value of -1