How to optimize exporting data to excel in Excel Interop? - excel

Question

I am using Excel interop to create excel workbooks from my query results. When there are thousands of records it takes a long time for the workbook to be generated. The below code is a sample of how I am populating the cells.
RowNo = 1
For i = 1 To 4000
ColNo = 1
For j = 1 To 5
Dim cell As excel.Range = ws.Cells(RowNo, ColNo)
Dim value = j
cell.Value = value
ColNo = ColNo + 1
Next
RowNo = RowNo + 1
Next
For the above code to run it takes more than a minute. How can I optimize it?

Answer 1

Found the answer. You can write data to an array and then write the array to the excel range rather than writing the data cell by cell. See http://www.clear-lines.com/blog/post/Write-data-to-an-Excel-worksheet-with-C-fast.aspx
private static void WriteArray(int rows, int columns, Worksheet worksheet)
{
var data = new object[rows, columns];
for (var row = 1; row <= rows; row++)
{
for (var column = 1; column <= columns; column++)
{
data[row - 1, column - 1] = "Test";
}
}
var startCell = (Range)worksheet.Cells[1, 1];
var endCell = (Range)worksheet.Cells[rows, columns];
var writeRange = worksheet.Range[startCell, endCell];
writeRange.Value2 = data;
}