Pass value in Crystal report - crystal-reports

Question

I add formula field region,fromdate,todate in report
i.e.
UPDATED IMAGE
Also I try this another method:
protected void Report_Click(object sender, EventArgs e)
{
data crystalReport = new data();
crystalReport.DataDefinition.FormulaFields["region"].Text = regiondrop.SelectedValue;
crystalReport.DataDefinition.FormulaFields["fromdate"].Text = fromdate.Value;
crystalReport.DataDefinition.FormulaFields["todate"].Text = todate.Value;
BindReport(crystalReport,Convert.ToDateTime(fromdate.Value), Convert.ToDateTime(todate.Value), regiondrop.SelectedValue);
}
This show error on page:
Error
This field name is not known. Details: errorKind Error in File temp_2c6994eb-49ef-432f-bfd7-af0eb80dc7ec 4032_6896_{5E54477E-F078-41DF-BD52-AF042B96DA53}.rpt: Error in formula fromdate: '{DataTable1.StartDate}' This field name is not known. Details: errorKind
Now this is working finally with the help of #Furtiro
public void BindReport(ReportDocument crystalReport, DateTime fromdate, DateTime todate, string region)
{
T1 t = new T1();
DateTime fdate = new DateTime(fromdate.Year, fromdate.Month, fromdate.Day, 0, 0, 0);
DateTime tdate = new DateTime(todate.Year, todate.Month, todate.Day, 23, 59, 59);
List<griddataresult_Result> dsc = t.griddataresult(fdate, tdate, region).ToList();
DataTable dt = new DataTable();
dt.Columns.Add("ID", typeof(int));
dt.Columns.Add("OwnerName", typeof(string));
dt.Columns.Add("RegNo", typeof(string));
foreach (var c in dsc)
{
dt.Rows.Add(c.ID, c.OwnerName, c.RegNo, c.total_voilatio, c.MileageAccumlation, c.MaxSpeed);
}
crystalReport.DataDefinition.FormulaFields["region"].Text = "'" + region + "'";
crystalReport.DataDefinition.FormulaFields["fromdate"].Text = "'" + fromdate + "'";
crystalReport.DataDefinition.FormulaFields["todate"].Text = "'" + todate + "'";
crystalReport.SetDataSource(dt);
CrystalReportViewer1.ReportSource = crystalReport;
CrystalReportViewer1.DataBind();
}

Answer 1

You can instanciate your report like an object , replace your line :
ReportDocument crystalReport = new ReportDocument();
By :
data crystalReport = new data();
Here data is the name of you .rpt class.
*Update *
You don't understand that ReportDocument is an object, your object here will be your data class.
So all the lines when you set doc = crystalreport are useless because you don't work on your crystalReport object but on other objects.
Second update :
I didn't see your access to the formula, you're not supposed to write the "#' in the name of your formula. My bad sorry , here's your working code :
protected void Report_Click(object sender, EventArgs e)
{
data crystalReport = new data();
crystalReport.DataDefinition.FormulaFields["region"].Text = "'" + regiondrop.SelectedValue.ToString() + "'";
crystalReport.DataDefinition.FormulaFields["fromdate"].Text = "'" + fromdate.Value.ToString() +"'";
crystalReport.DataDefinition.FormulaFields["todate"].Text = "'"+ todate.Value.ToString() + "'";
BindReport(crystalReport,Convert.ToDateTime(fromdate.Value), Convert.ToDateTime(todate.Value), regiondrop.SelectedValue);
}
Be careful about the dataType and parse when you write a formula in c# code, for example if you want to display some text in a formula dynamically you'll need to cast your data with quotes
Like report.DataDefinition.FormulaFields["yourformula"].Text ="'Hello world'";
Dont forget the quotes, simple or double quotes will works.
Best regards,