_AllocHand( ) API Library Routine

Visual FoxPro 9.0 SP2

_AllocHand( ) API Library Routine


MHANDLE _AllocHand(unsigned int hsize) unsigned int hsize; /* Size of new memory handle in bytes. */

Remarks

_AllocHand( ) returns 0 when there is insufficient memory to fulfill the request. Memory allocated with _AllocHand( ) isn't initialized, and must be freed after use.

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

Example

In The following example, a character is replicated in memory supplied by _AllocHand( ). The API function REPLTOMH( ) below returns the memory handle to Visual FoxPro. From Visual FoxPro the memory handle is passed to API functions, which expect a memory handle argument (passed as an integer, "I").

Visual FoxPro Code

	Copy Code
SET LIBRARY TO ALLOCHAN mh = REPLTOMH("x", 120) ? MHTOFOX(mh) ? LEN(MHTOFOX(mh)) ? MHTOFOX(mh) = FREEMH(mh)

C Code

	Copy Code
#include <pro_ext.h> // Replicate char argument to memory allocated with _AllocHand(). // Return the memory handle to Visual FoxPro. void FAR replToMH(ParamBlk FAR parm) { char FAR rep; char c = (char ) _HandToPtr(parm->p[0].val.ev_handle); MHANDLE mh; if ((mh = _AllocHand((int) parm->p[1].val.ev_long + 1)) == 0) { _Error(182); // "Insufficient memory" } _HLock(mh); rep = _HandToPtr(mh); _MemFill(rep, c, (int) parm->p[1].val.ev_long); rep[parm->p[1].val.ev_long] = '\0'; // null terminate _HUnLock(mh); _RetInt(mh, 10); } // Returns characters in memory handle. // Argument in call from Visual FoxPro // must be a valid Visual FoxPro memory handle. void FAR MHToFoxString(ParamBlk FAR parm) { char FAR string; MHANDLE mh = parm->p[0].val.ev_long; _HLock(mh); string = _HandToPtr(mh); _RetChar(string); _HUnLock(mh); } // Frees memory handle. Argument in call from // Visual FoxPro must be a valid // Visual FoxPro memory handle. void FAR freeMH(ParamBlk FAR parm) { _FreeHand((MHANDLE) parm->p[0].val.ev_long); } FoxInfo myFoxInfo[] = { {"REPLTOMH", (FPFI) replToMH, 2, "C,I"}, {"MHTOFOX", (FPFI) MHToFoxString, 1, "I"}, {"FREEMH", (FPFI) freeMH, 1, "I"}, }; FoxTable _FoxTable = { (FoxTable FAR ) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo };

Copy Code

#include <pro_ext.h>
//   Replicate char argument to memory allocated with _AllocHand().
//   Return the memory handle to Visual FoxPro.
void FAR replToMH(ParamBlk FAR *parm)
{
   char FAR *rep;
   char c = *(char *) _HandToPtr(parm->p[0].val.ev_handle);
   MHANDLE mh;
   if ((mh = _AllocHand((int) parm->p[1].val.ev_long + 1)) == 0)
   {
      _Error(182);  // "Insufficient memory"
   }
   _HLock(mh);
   rep = _HandToPtr(mh);
   _MemFill(rep, c, (int) parm->p[1].val.ev_long);
   rep[parm->p[1].val.ev_long] = '\0';  // null terminate
   _HUnLock(mh);
   _RetInt(mh, 10);
}
//   Returns characters in memory handle.
//   Argument in call from Visual FoxPro
//   must be a valid Visual FoxPro memory handle.
void FAR MHToFoxString(ParamBlk FAR *parm)
{
   char FAR *string;
   MHANDLE mh = parm->p[0].val.ev_long;
   _HLock(mh);
   string = _HandToPtr(mh);
   _RetChar(string);
   _HUnLock(mh);
}
//   Frees memory handle.  Argument in call from
//   Visual FoxPro must be a valid
//   Visual FoxPro memory handle.
void FAR freeMH(ParamBlk FAR *parm)
{
   _FreeHand((MHANDLE) parm->p[0].val.ev_long);
}
FoxInfo myFoxInfo[] = {
   {"REPLTOMH", (FPFI) replToMH, 2, "C,I"},
   {"MHTOFOX", (FPFI) MHToFoxString, 1, "I"},
   {"FREEMH", (FPFI) freeMH, 1, "I"},
};
FoxTable _FoxTable = {
   (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
};

_AllocHand( ) API Library Routine

Remarks

Example

Visual FoxPro Code

C Code

See Also

Reference

Concepts

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