After creating the extension method of DataTableToExcel, let’s create that DataTable from a CSV file.

If you open a csv file in Excel, you’ll get all the information in 1 column. Now we create a usable xlsx file from out csv.

DataTable dt = new DataTable();
char separation = ',';//comma separated csv

//columns
string[] columns = fileContent[0].Split(separation);
for (int i = 0; i < columns.Count(); i++)
{
    dt.Columns.Add(columns[i].Replace("\"", ""));//if the column name contains DoubleQuotes, let's remove it
}

//rows
for (int i = 1; i < fileContent.Count(); i++)
{
    string[] rowData = fileContent[i].Split(separation);
    string[] realRowData = new string[columns.Count()];
    StringBuilder finalString = new StringBuilder();
    int temp = 0;
                            
    for (int j = 0, k = 0; j < rowData.Count(); j++, k++) { if ((rowData[j].Count(x => x == '"') % 2 == 0))//checks if the string contains EVEN number of DoubleQuotes
        {
            realRowData[k] = quotesLogic((rowData[j]));
        }
        else if ((rowData[j].Count(x => x == '"') % 2 != 0))//If Number of DoubleQuotes are ODD
        {
            int c = rowData[j].Count(x => x == '"');
            temp = j;

            while (c % 2 != 0)//Go through all the next array cell till it makes EVEN number of DoubleQuotes.
            {
                finalString.Append(rowData[j] + ",");
                j++;
                c += rowData[j].Count(x => x == '"');
            }

            finalString.Append(rowData[j]);
            realRowData[k] = quotesLogic(finalString.ToString());
        }
        else continue;
    }

    if (realRowData[0].Trim() != "") dt.Rows.Add(realRowData);//if we have empty rows in Excel, we're gonna skip them
}

Now if you set this DataTable as source of a DataGridView, you’ll get a perfect table structure.