Copying one datatable selected column to another data table - asp.net

Question

I have a datatable, then I have all the column names of the datatable as checkbox, I want to display only those column records, for which user selected from the checkbox:
Below is the code, but I am not getting the desired result
var values = "";
string clmnm = "";
for (int i = 0; i < interestedIN.Items.Count; i++)
{
if (interestedIN.Items[i].Selected)
{
values += interestedIN.Items[i].Value + ",";
}
}
values = values.TrimEnd(',');
string[] words = values.Split(',');
DataTable dt = new DataTable();
dt = (DataTable)Session["dataset"];
DataTable dt1 = new DataTable();
foreach (string word in words)
{
dt1.Columns.Add(word, typeof(string));
if (clmnm == string.Empty)
{
clmnm = word.Trim();
}
else
{
clmnm += "," +word.Trim();
}
}
foreach (DataRow dr in dt.Rows)
{
string[] split = clmnm.Split(',');
int j =0;
string str = "";
string str2 = "";
while( j < split.Length)
{
str = split[j].ToString();
if (str2 == string.Empty)
{
str2 = "dr[\""+str.ToString()+"\"]";
}
else
{
str2 += "," + "dr[\""+str.ToString()+"\"]";
}
j+=1;
}
dt1.Rows.Add(str2);
}
then I am trying to export the result as an excel sheet: but getting the below excel sheet:

Answer 1

There is a lot of changes to be done to your code. Lets begin with selected columns from CheckBoxList. Try using List or Arrays to store which columns that user wants. Like
List<string> columns = new List<string>();
Then store the selected columns into the columns list. Then you need to add columns to your new DataTable dt1. As,
DataTable dt1 = new DataTable();
for (int i = 0; i < interestedIN.Items.Count; i++)
{
if (interestedIN.Items[i].Selected) //If user selected this columns checkbox.
{
columns.Add(interestedIN.Items[i].Text.Trim()); //Storing values to List.
dt1.Columns.Add(interestedIN.Items[i].Text.Trim()); //Adding columns to the DataTable.
}
}
Then you can loop through your original DataTable dt and store the values as below.
foreach (DataRow dr in dt.Rows)
{
DataRow dr1 = dt1.NewRow(); // Create new row which should have identical structure for inserting.
foreach(string col in columns)
{
dr1(col) = dr(col);
}
dt1.Rows.Add(dr1); //Add the row with the contents to the table.
}