_MemMove( ) API Library Routine


void _MemMove(void FAR dest, void FAR src, unsigned int length) void FAR dest; / Destination. / void FAR src; /* Starting position. / unsigned int length; / How many bytes to move. */

Overlapping moves are performed in the appropriate direction to prevent data corruption.

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

The following example uses _MemMove( ) to implement a substring function. From Visual FoxPro, MEMMOVE(s, n1, n2) returns the substring of s starting from position n1 and through position n2.

Visual FoxPro Code

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SET LIBRARY TO MEMMOVE ? MEMMOVE("Hello, world.", 8, 10) && returns "wor"

C Code

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#include <pro_ext.h> FAR Example(ParamBlk FAR parm) { int SubstrLen; MHANDLE bufferHandle; char FAR FirstDest; SubstrLen = parm->p[2].val.ev_long - parm->p[1].val.ev_long + 1; if ((bufferHandle = _AllocHand(SubstrLen + 1)) == 0) { _Error(182); // "Insufficient memory" } _HLock(bufferHandle); _HLock(parm->p[0].val.ev_handle); FirstDest = (char FAR ) _HandToPtr(parm->p[0].val.ev_handle) + parm->p[1].val.ev_long - 1; _MemMove(_HandToPtr(bufferHandle), FirstDest, SubstrLen); ((char FAR ) _HandToPtr(bufferHandle))[SubstrLen] = '\0'; _RetChar(_HandToPtr(bufferHandle)); _HUnLock(bufferHandle); _HUnLock(parm->p[0].val.ev_handle); } FoxInfo myFoxInfo[] = { {"MEMMOVE", (FPFI) Example, 3, "C,I,I"}, }; FoxTable _FoxTable = { (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo };

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#include <pro_ext.h>
FAR Example(ParamBlk FAR *parm)
{
   int SubstrLen;
   MHANDLE bufferHandle;
   char FAR *FirstDest;
   SubstrLen = parm->p[2].val.ev_long - parm->p[1].val.ev_long + 1;
   if ((bufferHandle = _AllocHand(SubstrLen + 1)) == 0)
   {
      _Error(182); // "Insufficient memory"
   }
   _HLock(bufferHandle);
   _HLock(parm->p[0].val.ev_handle);
   FirstDest = (char FAR *) _HandToPtr(parm->p[0].val.ev_handle) +
      parm->p[1].val.ev_long - 1;
   _MemMove(_HandToPtr(bufferHandle), FirstDest, SubstrLen);
   ((char FAR *) _HandToPtr(bufferHandle))[SubstrLen] = '\0';
   _RetChar(_HandToPtr(bufferHandle));
   _HUnLock(bufferHandle);
   _HUnLock(parm->p[0].val.ev_handle);
}
FoxInfo myFoxInfo[] = {
   {"MEMMOVE", (FPFI) Example, 3, "C,I,I"},
};
FoxTable _FoxTable = {
   (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
};

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Example

Visual FoxPro Code

C Code

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