Fastest way to write cells to Excel with Office Interop?

Accepted answer +24 upvotes

You should avoid reading and writing cell by cell if you can. It is much faster to work with arrays, and read or write entire blocks at once. I wrote a post a while back on reading from worksheets using C#; basically, the same code works the other way around (see below), and will run much faster, especially with larger blocks of data.

  var sheet = (Worksheet)Application.ActiveSheet;
  var range = sheet.get_Range("A1", "B2");
  var data = new string[3,3];
  data[0, 0] = "A1";
  data[0, 1] = "B1";
  data[1, 0] = "A2";
  data[1, 1] = "B2";
  range.Value2 = data;