.NET Excel Library - Import and Export Excel Data using C#

// Initialize Excel engine and application.
using ExcelEngine excelEngine = new ExcelEngine();
IApplication application = excelEngine.Excel;
application.DefaultVersion = ExcelVersion.Xlsx;

// Create a workbook and worksheet.
IWorkbook workbook = application.Workbooks.Create(1);
IWorksheet worksheet = workbook.Worksheets[0];

// Initialize and populate DataTable.
DataTable table = SampleDataTable();

// Import data from DataTable to the worksheet.
worksheet.ImportDataTable(table, true, 1, 1);

// Save the Excel document.
using FileStream outputStream = new FileStream("ImportDataTable.xlsx", FileMode.Create, FileAccess.Write);
workbook.SaveAs(outputStream);

// Method to create a sample DataTable.
private DataTable SampleDataTable()
{
    // Create DataTable with columns.
    DataTable table = new DataTable();
    table.Columns.Add("Dosage", typeof(int));
    table.Columns.Add("Drug", typeof(string));
    table.Columns.Add("Patient", typeof(string));
    table.Columns.Add("Date", typeof(DateTime));

    // Add sample data rows.
    table.Rows.Add(25, "Indocin", "David", DateTime.Now);
    table.Rows.Add(50, "Enebrel", "Sam", DateTime.Now);
    table.Rows.Add(10, "Hydralazine", "Christoff", DateTime.Now);
    table.Rows.Add(21, "Combivent", "Janet", DateTime.Now);
    table.Rows.Add(100, "Dilantin", "Melanie", DateTime.Now);

    return table;
}