_MemoChan( ) API Library Routine


FCHAN _MemoChan(int workarea) int workarea; /* Work area number. */

If no database is open in that work area or the database has no memo file, _MemoChan( ) returns – 1.

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

The following example retrieves the contents of a memo field. _MemoChan( – 1) returns a file channel to the memo file for the current work area. This FCHAN is used as an argument to the low-level file I/O API callbacks.

Visual FoxPro Code

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SET LIBRARY TO MEMOCHAN CREATE TABLE WMemo (MemoField M) APPEND BLANK REPLACE MemoField WITH "Hello, World." ? GETMEMO(@MemoField)

C Code

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#include <pro_ext.h> FAR FindMemoEx(ParamBlk FAR parm) { Locator FAR memoFldLoc; FCHAN fchMemo; char FAR memoContents; int memoLen; long loc; if ((fchMemo = _MemoChan(-1)) == -1) { _UserError("_MemoChan() failed"); } memoFldLoc = &parm->p[0].loc; if ((loc = _FindMemo(memoFldLoc)) < 0) { _UserError("_FindMemo() failed"); } if ((memoLen = _MemoSize(memoFldLoc)) < 0) { _UserError("_MemoSize() failed"); } if ((memoContents = _Alloca(memoLen + 1)) == 0) { _Error(182); // "Insufficient memory" } _FSeek(fchMemo, loc, FS_FROMBOF); _FRead(fchMemo, memoContents, memoLen); memoContents[memoLen] = '\0'; _RetChar(memoContents); } FoxInfo myFoxInfo[] = { {"GETMEMO", (FPFI) FindMemoEx, 1, "R"}, }; FoxTable _FoxTable = { (FoxTable FAR ) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo };

Copy Code

#include <pro_ext.h>
FAR FindMemoEx(ParamBlk FAR *parm)
{
   Locator FAR *memoFldLoc;
   FCHAN fchMemo;
   char FAR *memoContents;
   int memoLen;
   long loc;
   if ((fchMemo = _MemoChan(-1)) == -1)
   {
      _UserError("_MemoChan() failed");
   }
   memoFldLoc = &parm->p[0].loc;
   if ((loc = _FindMemo(memoFldLoc)) < 0)
   {
      _UserError("_FindMemo() failed");
   }
   if ((memoLen = _MemoSize(memoFldLoc)) < 0)
   {
      _UserError("_MemoSize() failed");
   }
   if ((memoContents = _Alloca(memoLen + 1)) == 0)
   {
      _Error(182); // "Insufficient memory"
   }
   _FSeek(fchMemo, loc, FS_FROMBOF);
   _FRead(fchMemo, memoContents, memoLen);
   memoContents[memoLen] = '\0';
   _RetChar(memoContents);
}
FoxInfo myFoxInfo[] = {
   {"GETMEMO", (FPFI) FindMemoEx, 1, "R"},
};
FoxTable _FoxTable = {
   (FoxTable FAR *) 0, sizeof(myFoxInfo)/sizeof(FoxInfo), myFoxInfo
};

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Visual FoxPro Code

C Code

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