In this document, let us see how to export a multidimensional array to an Excel file and add formatting to the contents while writing the Excel file.

Step 1: Create a web application and declare a property dt of type DataTable; see:

public partial class _Default : System.Web.UI.Page
{
private DataTable _dt;
public DataTable dt
{
get
 {
return _dt;
}
set
 {
_dt = value;
}
}

Step 2: I have added Gridview_Result as a GridView and set AutoGenerateColumns to True because we are going to create columns at runtime.

<asp:GridView runat="server" ID="GridView_Result" AutoGenerateColumns="True">
</asp:GridView>

Step 3: Now we are going to declare a multidimensional array in pageload and convert it to a datatable which I will bind with a GridView and after that we can export this datatable to an Excel file. Check the comments in the code to learn in detail.

protected void Page_Load(object sender, EventArgs e)

{

//declare multidimensional array.. i am declaring double array.

double[,] items = new double[100, 15];

//create datatable object

dt = new DataTable();

//Get the count of number of columns need to create for the array

for (int dimension = 0; dimension <= items.GetUpperBound(items.Rank - 1); dimension++)

{

//set column name as column+ column number

dt.Columns.Add("Column" + (dimension + 1));

}

//Now for each rows in array, get the column value and set it to datatable rows and columns

for (int element = 0; element <= items.GetUpperBound(items.Rank - 2); element++)

{

DataRow row = dt.NewRow();

for (int dimension = 0; dimension <= items.GetUpperBound(items.Rank - 1); dimension++)

{

row["Column" + (dimension + 1)] = items[element, dimension];

}

dt.Rows.Add(row);

}

GridView_Result.DataSource = dt;

GridView_Result.DataBind();

}

Step 4: I have written the following method which will convert a datatable to an Excel file. In this method, I added a font, made the headers bold and added a border. You can customize the method as per your need.

private void ExporttoExcel(DataTable table)

{

HttpContext.Current.Response.Clear();

HttpContext.Current.Response.ClearContent();

HttpContext.Current.Response.ClearHeaders();

HttpContext.Current.Response.Buffer = true;

HttpContext.Current.Response.ContentType = "application/ms-excel";

HttpContext.Current.Response.Write(@"<!DOCTYPE HTML PUBLIC ""-//W3C//DTD HTML 4.0 Transitional//EN"">");

HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=Reports.xls");

HttpContext.Current.Response.Charset = "utf-8";

HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("windows-1250");

//sets font

HttpContext.Current.Response.Write("<font style='font-size:10.0pt; font-family:Calibri;'>");

HttpContext.Current.Response.Write("<BR><BR><BR>");

//sets the table border, cell spacing, border color, font of the text, background, foreground, font height

HttpContext.Current.Response.Write("<Table border='1' bgColor='#ffffff' " +

"borderColor='#000000' cellSpacing='0' cellPadding='0' " +

"style='font-size:10.0pt; font-family:Calibri; background:white;'> <TR>");

//am getting my tables's column count

int columnscount = table.Columns.Count;

for (int j = 0; j < columnscount; j++)

{ //write in new column

HttpContext.Current.Response.Write("<Td>");

//Get column headers and make it as bold in excel columns

HttpContext.Current.Response.Write("<B>");

HttpContext.Current.Response.Write(table.Columns[j].ColumnName.ToString());

HttpContext.Current.Response.Write("</B>");

HttpContext.Current.Response.Write("</Td>");

}

HttpContext.Current.Response.Write("</TR>");

foreach (DataRow row in table.Rows)

{//write in new row

HttpContext.Current.Response.Write("<TR>");

for (int i = 0; i < table.Columns.Count; i++)

{

HttpContext.Current.Response.Write("<Td>");

HttpContext.Current.Response.Write(row[i].ToString());

HttpContext.Current.Response.Write("</Td>");

}

HttpContext.Current.Response.Write("</TR>");

}

HttpContext.Current.Response.Write("</Table>");

HttpContext.Current.Response.Write("</font>");

HttpContext.Current.Response.Flush();

HttpContext.Current.Response.End();

}

Step 5: Add a button and in the buttonclick event call the preceding method by ing a parameter; see:

 protected void Btn_Export_Click(object sender, EventArgs e)
{
ExporttoExcel(dt);
}

Run the solution and export the Excel and check the columns and rows. For the complete source code, please find the attached solution.