（C＃-Excel）如何为每个现有行的新列写一个公式？

Question

Say you have an excel file with a bunch of numbers and rows, about 100 rows.

I want to programatically write a column with a formula that adds the values of a bunch of fields together for each existing row.

So first of all, of course, I would create the Openfiledialog for the Excel file, find the path, open it up through OleDb. Got this down. Now say I have the following table:

[ Friends | Money | Money Lost | Days passed | Solution ]

Bilbo , 50 , 50 , 7 , *Formula here

Bilso , 80 , 50 , 7 , *Formula here

etc...

Problem is, I don't have an exact number for the rows so I'll have to enumerate whatever is found by the OleDb connection. The formula would be something like =(B2-C2)*D2 but 2 is also wrong and it would have to be relative to whatever row it's on, ie: row 3 would be =(B3-C3)*D3. I'm not sure how to do this.

I found out writing directly to the cell also doesn't make the formula process the numbers outright.

=====

EDIT:

    private Excel.Application Xls;
    private Excel.Workbooks WBs;
    private Excel.Workbook WB;
    private Excel.Worksheet WS;
    private Excel.Sheets SS;
    Excel.Range cellsRange = null;
    Excel.Range columnRange = null;
    Excel.Range rowRange = null;
    int numberOfColumns = 0;
    int numberOfRows = 0;
    private void btnColumn_Click(object sender, EventArgs e)
    {
        if (btnColumn.FlatStyle == FlatStyle.Flat)
            btnColumn.FlatStyle = FlatStyle.Standard;
        else
        {
            btnColumn.FlatStyle = FlatStyle.Flat;
        }

        OpenFileDialog openFileDialog = new OpenFileDialog();
        openFileDialog.Filter = "Excel Files|*.xls;*.xlsx";
        openFileDialog.ShowDialog();
        string pather = openFileDialog.FileName;

        if (pather == "" || pather == " " || pather == null)
        {
            return;
        }

        if (!string.IsNullOrEmpty(openFileDialog.FileName))
        {
            try
            {
                Xls = new Excel.Application();
                WBs = Xls.Workbooks;
                WB = WBs.Open(pather, 0, false, 5, "", "", true,
                    XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
                SS = WB.Worksheets;
                WS = SS.get_Item(1);                    
                cellsRange = WS.Cells;
                columnRange = cellsRange.Columns;
                rowRange = cellsRange.Rows;
                numberOfColumns = columnRange.Count;
                numberOfRows = rowRange.Count;
                int LastCell = numberOfColumns+1;
                WS.Cells[1, LastCell] = "Tax Formula";
                for (int i = 2; i < numberOfRows; i++)
                {
                    //string niceFormula = "=SUM(L" + i + ",M" + i + ")*N"+ i ;
                    //WS.Cells[i, LastCell].Formula = niceFormula;
                    WS.Cells[i, LastCell].Value = (WS.Cells[i, 12] + WS.Cells[i, 13]) * WS.Cells[i, 14];
                }
                //==========================
                WB.Save();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Write Excel: " + ex.Message);
            }
            finally
            {
                GC.Collect();
                GC.WaitForPendingFinalizers();
                WB.Close();
                Xls.Quit();

                releaseObject(cellsRange);
                releaseObject(columnRange);
                releaseObject(rowRange);
                releaseObject(SS);
                releaseObject(WS);
                releaseObject(WBs);
                releaseObject(WB);
                releaseObject(Xls);
            }
        MessageBox.Show("Finished Updating File", "Task complete");
    }
}

Anyone know why this code is throwing the following error on write attempt?

HRESULT: 0x800A03EC

Repasted entire code for your convenience. It's still spitting out the HRESULT error.

Targeted item is 4 rows deep with 1 row of headers and about 16 columns wide.

Answer 1

Edit:

You may want to try this:

numberOfColumns = WS.UsedRange.Columns.CountLarge;
numberOfRows = WS.UsedRange.Rows.CountLarge;

Ugh, also change them to long instead of int if you use CountLarge instead of Count

Okay - I got this working finally - no clue why I was having so many issues.

For me, I apparently have to make the application visible or it doesn't work.

There may be another workaround - I pulled it from here: https://stackoverflow.com/a/17061714/1274820

This code worked for me finally:

Note that this is a console application (figured I would rule that out), but you should just be able to add the magic lines.

Application excelApp = new Application();
excelApp.SheetsInNewWorkbook = 1;
////////////////////////////////////////////
//Add these lines to make it work???
////////////////////////////////////////////
try {
    excelApp.Visible = true;
}
catch {} 
////////////////////////////////////////////
Workbook excelWB = excelApp.Workbooks.Open(@"C:\test.xls", Type.Missing, false);
_Worksheet excelWS = excelWB.Sheets[1];
Range cellsRange = excelWS.UsedRange;
long LastCell = cellsRange.Columns.CountLarge + 1;
long numberOfRows = cellsRange.Rows.CountLarge;
excelWS.Cells[1, LastCell] = "Tax Formula";
for (int i = 2; i <= numberOfRows; i++)
{
    string niceFormula = "=SUM(L" + i + ",M" + i + ")*N" + i;
    excelWS.Cells[i, LastCell].Formula = niceFormula;
}
excelWB.Close(true);
excelApp.Quit();

Before:

After:

How to fill a DataTable with an excel spreadsheet:

//////////////////////////////////////////////////////////////////////////////////
//This function is absolute magic >.> - Fill DataTable with excel spreadsheet
//HDR=YES means "Spreadsheet has headers" Change to NO if not.
//name = "Log"; - This is the Sheet name to pull the data from
//////////////////////////////////////////////////////////////////////////////////
//oconn takes an SQL like command (Select Everything from name sheet) using con
//HDR=YES means that our data has headers :)
//////////////////////////////////////////////////////////////////////////////////
String constr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + copyToPath + ";Extended Properties='Excel 12.0 XML;HDR=YES;';";
OleDbConnection con = new OleDbConnection(constr);
OleDbCommand oconn = new OleDbCommand("Select * From [Log$]", con);
con.Open();
OleDbDataAdapter sda = new OleDbDataAdapter(oconn);
DataTable data = new DataTable();
sda.Fill(data);
con.Close();
//////////////////////////////////////////////////////////////////////////////////

Answer 2

Why not use the R1C1 reference style? That way your formula does not need to be relative to the column.

For reference: https://excelmate.wordpress.com/2013/04/22/excel-r1c1-reference-style-vs-a1/