Tried and tested
private void button1_Click(object sender, EventArgs e)
{
object xlApp;
object xlWbCol;
object xlWb;
object xlSheet;
object xlRange;
object xlWsCol;
Type tp;
tp = Type.GetTypeFromProgID("Excel.Application");
xlApp = Activator.CreateInstance(tp);
object[] parameter = new object[1];
parameter[0] = true;
xlApp.GetType().InvokeMember("Visible", BindingFlags.SetProperty, null, xlApp, parameter);
xlApp.GetType().InvokeMember("UserControl", BindingFlags.SetProperty, null, xlApp, parameter);
xlWbCol = xlApp.GetType().InvokeMember("Workbooks", BindingFlags.GetProperty, null, xlApp, null);
xlWb = xlWbCol.GetType().InvokeMember("Add", BindingFlags.InvokeMethod, null, xlWbCol, null);
xlWsCol = xlWb.GetType().InvokeMember("WorkSheets", BindingFlags.GetProperty, null, xlApp, null);
xlSheet = xlWb.GetType().InvokeMember("Add", BindingFlags.InvokeMethod, null, xlWsCol, null);
xlRange = xlSheet.GetType().InvokeMember("Cells", BindingFlags.GetProperty, null, xlSheet, new object[2] { 1, 1 });
xlRange.GetType().InvokeMember("Value", BindingFlags.SetProperty, null, xlRange, new object[] { "1-1-2012" });
object cols = xlRange.GetType().InvokeMember("Columns", BindingFlags.GetProperty, null, xlRange, null);
cols.GetType().InvokeMember("AutoFit", BindingFlags.InvokeMethod, null, cols, null);
cols.GetType().InvokeMember("NumberFormat", BindingFlags.SetProperty, null, cols, new object[1] { "DD/MM/YYYY" });
}
Note : Add using System.Reflection;To Top
Followup
For autofit for usedrangeit works
private void button1_Click(object sender, EventArgs e)
{
object xlApp;
object xlWbCol;
object xlWb;
object xlSheet;
object xlRangeUsdRng;
object xlRange;
object xlWsCol;
Type tp;
tp = Type.GetTypeFromProgID("Excel.Application");
xlApp = Activator.CreateInstance(tp);
object[] parameter = new object[1];
parameter[0] = true;
xlApp.GetType().InvokeMember("Visible", BindingFlags.SetProperty, null, xlApp, parameter);
xlApp.GetType().InvokeMember("UserControl", BindingFlags.SetProperty, null, xlApp, parameter);
xlWbCol = xlApp.GetType().InvokeMember("Workbooks", BindingFlags.GetProperty, null, xlApp, null);
xlWb = xlWbCol.GetType().InvokeMember("Add", BindingFlags.InvokeMethod, null, xlWbCol, null);
xlWsCol = xlWb.GetType().InvokeMember("WorkSheets", BindingFlags.GetProperty, null, xlApp, null);
xlSheet = xlWb.GetType().InvokeMember("Add", BindingFlags.InvokeMethod, null, xlWsCol, null);
xlRange = xlSheet.GetType().InvokeMember("Cells", BindingFlags.GetProperty, null, xlSheet, new object[2] {5, 6 });
xlRange.GetType().InvokeMember("Value", BindingFlags.SetProperty, null, xlRange, new object[] { "1-1-2012" });
xlRangeUsdRng = xlSheet.GetType().InvokeMember("UsedRange", BindingFlags.GetProperty, null, xlSheet, null);
object cols = xlRangeUsdRng.GetType().InvokeMember("EntireColumn", BindingFlags.GetProperty, null, xlRangeUsdRng, null);
cols.GetType().InvokeMember("AutoFit", BindingFlags.InvokeMethod, null, cols, null);
}