I have a button on my aspx page to download the gridview data to Excel. I am using SpreadsheetGear.dll. It worked nicely until the customer asked me to format the currency fields.

So this is my loop to format:

Code:
            System.Data.DataTable dtWarranties;
            dtWarranties = ds.Tables[0];

            // Format currency fields.
            double doubleOut;
            for (int i = 0; i < dtWarranties.Rows.Count; ++i)
            { 
                for (int j = 3; j < 6; ++j)
                {
                    if (Double.TryParse(Convert.ToString(dtWarranties.Rows[i].ItemArray[j]), out doubleOut))
                        dtWarranties.Rows[i].ItemArray[j] = String.Format("${0:0.00}", doubleOut);  
                }
            }
As I am stepping through debugging, I query this:
? String.Format("${0:0.00}", doubleOut)
"$1569.00
But I query the left side of the assignment, and it is still unformatted:
? dtWarranties.Rows[i].ItemArray[j]
"1569"

Why won't it "take" the format?