Write to cell in excel using c#

Question

I created a visual studio excel workbook project which contains ThisWorkbook class and I then included a functions class so that I can create my own excel function. I am trying to write a value to a cell using c# through the use of the function. I can write to the excel cell through the function class but only by creating a new application/workbook. So everytime I use this excel function, it will open new instance of excel. Is there a way I can write to a cell in the current excel workbook that is already opened?

Answer 1

You probably create a new Excel application, instead of connecting to the active Excel application.

Use the GetActiveObject to get your reference to the Excel application object.

Answer 2

Look, I tried and this code works:

private void ThisWorkbook_Startup(object sender, System.EventArgs e)
{
    Excel.Worksheet ws = (Excel.Worksheet)(sender as Workbook).ActiveSheet;

    System.Random rnd = new System.Random();

    for (int i = 1; i <= 20; i++)
        ws.Cells[i, 2] = rnd.Next(100);
}

so as you see you can access the Worksheet and use ws.Cells to manipulate cell values.

there are plenty of examples here:

Understanding the Excel Object Model from a .NET Developer's Perspective