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 _FOpen( ) API Library Routine

Assigns a Visual FoxPro channel to an existing file.

FCHAN _FOpen(char FAR *filename, int mode)
char FAR *filename;         /* Name of existing file */
int mode;                     /* Mode option. */

Expand imageRemarks

The following mode options are available: FO_READONLY, FO_WRITEONLY, and FO_READWRITE. _FOpen( ) opens a file with exclusive access. _FOpen( ) returns the file channel if it's successful in opening the file, or returns – 1 if it can't open the file.

For more information on how to create an API library and integrate it with Visual FoxPro, see Accessing the Visual FoxPro API.

Expand imageExample

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

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SET LIBRARY TO FOPEN

C Code

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#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
};

Expand imageSee Also