using System;
using System.Windows.Forms;
using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Shared;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            ReportDocument cryRpt = new ReportDocument();
            cryRpt.Load("PUT CRYSTAL REPORT PATH HERE\CrystalReport1.rpt");

            ParameterFieldDefinitions crParameterFieldDefinitions ;
            ParameterFieldDefinition crParameterFieldDefinition ;
            ParameterValues crParameterValues = new ParameterValues();
            ParameterDiscreteValue crParameterDiscreteValue = new ParameterDiscreteValue();

            crParameterDiscreteValue.Value = textBox1.Text;
            crParameterFieldDefinitions = cryRpt.DataDefinition.ParameterFields;
            crParameterFieldDefinition = crParameterFieldDefinitions["Customername"];
            crParameterValues = crParameterFieldDefinition.CurrentValues;

            crParameterValues.Clear();
            crParameterValues.Add(crParameterDiscreteValue);
            crParameterFieldDefinition.ApplyCurrentValues(crParameterValues);

            crystalReportViewer1.ReportSource = cryRpt;
            crystalReportViewer1.Refresh(); 

        }
    }
}