В следующем примере показано, как с помощью программы _EdUndoOn( ) группи овать операции редактирования, чтобы потом отменить их все сразу с помощью _EdUndo( ).

Код Visual FoxPro

SET LIBRARY TO EDUNDOON

= EDUNDOON("x") && edit file "x"

Код C

#include <pro_ext.h>

#define TRUE 1

#define FALSE 0

FAR Example(ParamBlk FAR *parm)

{

char FAR *pFileName;

WHANDLE wh;

if (!_SetHandSize(parm->p[0].val.ev_handle,

parm->p[0].val.ev_length+1))

{

_Error(182); // "Insufficient memory"

}

_HLock(parm->p[0].val.ev_handle);

pFileName = (char FAR *) _HandToPtr(parm->p[0].val.ev_handle);

pFileName[parm->p[0].val.ev_length] = '\0';

wh = _EdOpenFile(pFileName, FO_READWRITE);

_HUnLock(parm->p[0].val.ev_handle);

_EdUndoOn(wh, TRUE); // start undo group

_EdSetPos(wh, _EdGetLinePos(wh, 13));

_EdInsert(wh, "Hello, world\n", _StrLen("Hello, world\n"));

_EdSelect(wh, _EdGetLinePos(wh, 14), _EdGetLinePos(wh, 16));

_EdIndent(wh, 1);

_EdUndoOn(wh, FALSE); // end undo group

_EdUndoOn(wh, TRUE); // start another undo group

_EdSelect(wh, _EdGetLinePos(wh, 9), _EdGetLinePos(wh, 12));

_EdDelete(wh);

_EdSetPos(wh, _EdGetLinePos(wh, 13));

_EdInsert(wh, "Hello, world\n", _StrLen("Hello, world\n"));

_Execute("WAIT WINDOW 'Press any key to undo changes.'");

_EdUndoOn(wh, TRUE); // undoes to start of undo group

}

FoxInfo myFoxInfo[] = {

{"EDUNDOON", (FPFI) Example, 1, "C"},

};

FoxTable _FoxTable = {

(FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo

};