_FOpen( ) API Library Routine Example

The following example creates a test file. It then opens the file in FO_READONLY mode and attempts to write to it. As a result _FError( ) returns 5 for "Access denied." Next, the example opens the test file in FO_WRITEONLY mode, and attempts to read from it. Again, _FError( ) returns 5.

Visual FoxPro Code

SET LIBRARY TO FOPEN 

C Code

#include <pro_ext.h>

void putLong(long n)
{
   Value val;

   val.ev_type = 'I';
   val.ev_long = n;
   val.ev_width = 10;

   _PutValue(&val);
}

#define BUFFSIZE 256
static char lineBuffer[BUFFSIZE];

FAR Example(ParamBlk FAR *parm)
{
   FCHAN fchan;

   fchan = _FCreate("temp.tmp", FC_NORMAL);
   _FCHSize(fchan, 8192);
   _FClose(fchan);

   fchan = _FOpen("temp.tmp", FO_READONLY);
   _FPuts(fchan, "Hello, world");
   _PutStr("\nAttempt to _FPuts() to file _FOpen()d FO_READONLY");
   _PutStr("\n_FError() ="); putLong(_FError());
   _FClose(fchan);

   fchan = _FOpen("temp.tmp", FO_WRITEONLY);
   _FGets(fchan, lineBuffer, BUFFSIZE);
   _PutStr("\nAttempt to _FGets() from file _FOpen()d FO_WRITEONLY");
   _PutStr("\n_FError() ="); putLong(_FError());
   _FClose(fchan);
}

FoxInfo myFoxInfo[] = {
   {"FOPEN", (FPFI) Example, CALLONLOAD, ""},
};
FoxTable _FoxTable = {
   (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
};