_FSeek( ) API Library Routine Example
The following example consists of one API routine which takes two parameters, a file name, and an integer. It opens the file. Using _FSeek( ) with the FS_FROMBOF flag, it then moves the file pointer to the offset position specified by the integer parameter, and reads a single byte from the file at that position.
SET LIBRARY TO FSEEK
fc = FCREATE("x", 0)
= FPUTS(fc, "abcdefghijklmnopqrstuvwxyz", 26)
= FCLOSE(fc)
? XFSEEK("x", 2) && displays 3rd byte of file x as an integer
? XFSEEK("x", 4) && displays 5th byte of file x as an integer
DELETE FILE x
#include <pro_ext.h>
FAR Example(ParamBlk FAR *parm)
{
FCHAN fchan;
char x;
// Null terminate file name
if (!_SetHandSize(parm->p[0].val.ev_handle,
parm->p[0].val.ev_length+1))
{
_Error(182); // "Insufficient memory"
}
_HLock(parm->p[0].val.ev_handle);
((char FAR *) _HandToPtr(parm->p[0].val.ev_handle))
[parm->p[0].val.ev_length] = '\0';
if ((fchan=_FOpen((char FAR*)_HandToPtr(parm->p[0].val.ev_handle),
FC_NORMAL)) < 0)
{
_UserError("Could not open file.");
}
_HUnLock(parm->p[0].val.ev_handle);
_FSeek(fchan, parm->p[1].val.ev_long, FS_FROMBOF);
_FRead(fchan, &x, 1);
_RetInt(x, 10);
_FClose(fchan);
}
FoxInfo myFoxInfo[] = {
{"XFSEEK", (FPFI) Example, 2, "C,I"},
};
FoxTable _FoxTable = {
(FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
};