How To Use MFC to Automate Excel and Fill a Range with an Array

This article demonstrates how to automate Microsoft Excel and fill a multi-cell range with an array of values.

To fill a multi-cell range without populating the cells one-by-one, you must create a two-dimensional variant SAFEARRAY which you pass to Excel by calling the SetValue function for the Range object. The following steps illustrate this process.

Notes for Automating Microsoft Excel 2000 and 2002

The sample code in this article uses class wrappers generated from the Excel 97 object library (Excel 8.olb). With slight modification, this code can be applied to an Automation client that uses class wrappers for Excel 2000 (Excel9.olb) or Excel 2002 (Excel.olb). For additional information about using the sample code described in this article with the Microsoft Excel 2000 or 2002 type library, please click the article number below to view it in the Microsoft Knowledge Base:

Steps to Create Project

1. Follow steps 1 through 12 in the following article in the Microsoft Knowledge Base to create a sample project that uses the IDispatch interfaces and member functions defined in the Excel8.olb type library:
   178749� How To Create an Automation Project Using MFC and a Type Library
2. To the dialog box created in steps 4 and 5 of the parent article 178749� , add the following controls with properties as specified. Also add the corresponding member variables:

                                     Member                Member
         Control   Name              Variable Type         Variable Name
         -----------------------------------------------------------------
         Edit      IDC_STARTINGCELL  m_sStartingCell       CString
         Edit      IDC_NUMROWS       m_iNumRows            short
         Edit      IDC_NUMCOLS       m_iNumCols            short
         CheckBox  IDC_STRING        m_bFillWithStrings    BOOL
   					

3. At the top of the AutoProjectDlg.cpp file, add the following line:

         #include "excel8.h"
   					

4. Add the following code to CAutoProjectDlg::OnRun() in the AutoProjectDlg.cpp file.

   Sample Code

         // OLE Variant for Optional.
         COleVariant VOptional((long)DISP_E_PARAMNOTFOUND, VT_ERROR);
   
         _Application objApp;
   
         _Workbook objBook;
         Workbooks objBooks;
         Worksheets objSheets;
         _Worksheet objSheet;
         Range range;
   
         if(!UpdateData(TRUE))
         {
            return;
         }
   
         // Instantiate Excel and start a new workbook.
         objApp.CreateDispatch("Excel.Application");
         objBooks = objApp.GetWorkbooks();
         objBook = objBooks.Add(VOptional);
         objSheets = objBook.GetWorksheets();
         objSheet = objSheets.GetItem(COleVariant((short)1));
   
         //Get the range where the starting cell has the address
         //m_sStartingCell and it's dimensions are m_iNumRows x m_iNumCols.
         range = objSheet.GetRange(COleVariant(m_sStartingCell),
                                   COleVariant(m_sStartingCell));
         range = range.GetResize(COleVariant(m_iNumRows),
                                 COleVariant(m_iNumCols));
   
         //*** Fill the range with an array of values.
   
         //Create the SAFEARRAY.
         COleSafeArray saRet;
         DWORD numElements[2];
         numElements[0]= m_iNumRows;   //Number of rows in the range.
         numElements[1]= m_iNumCols;   //Number of columns in the range.
   
         if(m_bFillWithStrings)
         {
            saRet.Create(VT_BSTR, 2, numElements);
         }
         else
         {
            saRet.Create(VT_R8, 2, numElements);
         }
   
         //Fill the SAFEARRAY.
         long index[2];
         long iRow;
         long iCol;
   
         for(iRow=0;iRow<=m_iNumRows-1;iRow++)
         {
            for(iCol=0;iCol<=m_iNumCols-1;iCol++)
            {
               index[0] = iRow;
               index[1] = iCol;
               if(m_bFillWithStrings)      //Fill with Strings.
               {
                  VARIANT v;
                  CString s;
                  VariantInit(&v);
                  v.vt = VT_BSTR;
                  s.Format("r%dc%d", iRow, iCol);
                  v.bstrVal = s.AllocSysString();
                  saRet.PutElement(index, v.bstrVal);
                  SysFreeString(v.bstrVal);
                  VariantClear(&v);
               }
               else                     //Fill with Numbers.
               {
                  double d;
                  d = (iRow*1000) + iCol;
                  saRet.PutElement(index, &d);
               }
            }
         }
   
         //Set the range value to the SAFEARRAY.
         range.SetValue(COleVariant(saRet));
         saRet.Detach();
   
         //Return control of Excel to the user.
         objApp.SetVisible(TRUE);
         objApp.SetUserControl(TRUE);
   					

5. Compile and Run the project.
6. Specify the following values for the controls on the dialog box:

         Control               Contents
         ------------------------------
         IDC_STARTINGCELL      A1
         IDC_NUMROWS           10
         IDC_NUMCOLS           5
         IDC_STRING            True
   						

   Click OK.
   
   Results: A new workbook is generated and cells A1:E10 of the first worksheet are populated with string values.
7. Specify the following values for the controls on the dialog box:

         Control               Contents
         ------------------------------
         IDC_STARTINGCELL      C3
         IDC_NUMROWS           2
         IDC_NUMCOLS           9
         IDC_STRING            False
   						

   Click OK.
   
   Results: A new workbook is generated and cells C3:K4 of the first worksheet are populated with numeric values.

For more information about automating Microsoft Excel using MFC, please see the following articles in the Microsoft Knowledge Base: