pass comboboxes values to a report

You can pass parameters to Report using ReportParameter and ReportParameterCollection Class.

See this example code :

ReportParameterCollection mreportParameterCollection = new ReportParameterCollection();
mreportParameterCollection.Add(new ReportParameter("param1", this.textbox1.text));
mreportParameterCollection.Add(new ReportParameter("param2", this.textbox2.text));
this.ReportViewer1.LocalReport.SetParameters(mreportParameterCollection );
this.ReportViewer1.RefreshReport();

ReportParameter Class : https://msdn.microsoft.com/en-us/library/microsoft.reporting.webforms.reportparameter%28v=vs.90%29.aspx

ReportParameterCollection Class : https://msdn.microsoft.com/en-us/library/microsoft.reportingservices.reportrendering.reportparametercollection.aspx

For more information : http://www.c-sharpcorner.com/Forums/Thread/213920/how-to-pass-two-textboxs-value-to-reportviewer-in-C-Sharp-using.aspx

Hi, Please check below links :

Passing Data between Windows Forms

http://www.codeproject.com/Articles/17371/Passing-Data-between-Windows-Forms

Using a delegate to pass data between two forms

http://www.codeproject.com/Articles/6456/Using-a-delegate-to-pass-data-between-two-forms