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_HUnLock( ) API Library Routine

  • Article

Unlocks a memory handle so that Visual FoxPro can access it during memory reorganization.

void _HUnLock(MHANDLE hand)
MHANDLE hand;            /* Memory handle. /

Remarks

_HUnLock( ) doesn't cause memory reorganization.

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

Example

The following example uses _RetDateStr( ) to return a Visual FoxPro date type, assuming that the character parameter is a proper date. It issues _HUnLock( ) when memory handles no longer need to be locked, because the performance of Visual FoxPro can be adversely affected by locked memory handles.

Visual FoxPro Code

SET LIBRARY TO HUNLOCK 
? DATES("2/16/95")  && returns date {02/16/95}

C Code

#include <pro_ext.h>

void FAR dates(ParamBlk FAR *parm)
{
   MHANDLE mh;
   char FAR *instring;

   if ((mh = _AllocHand(parm->p[0].val.ev_length + 1)) == 0) 
   {
      _Error(182); // "Insufficient memory"
   }
   _HLock(parm->p[0].val.ev_handle);
   instring = _HandToPtr(parm->p[0].val.ev_handle);
   instring[parm->p[0].val.ev_length] = '\0';
   _RetDateStr(instring);
   _HUnLock(parm->p[0].val.ev_handle);
}

FoxInfo myFoxInfo[] = {
   {"DATES", (FPFI) dates, 1, "C"}
};
FoxTable _FoxTable = {
   (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
};

See Also

_AllocHand( ) API Library Routine | _FreeHand( ) API Library Routine | _GetHandSize( ) API Library Routine | _HandToPtr( ) API Library Routine | _HLock( ) API Library Routine | _MemAvail( ) API Library Routine | _SetHandSize( ) API Library Routine