C#

public class MyFirstForm : Form
{
   public int Foo = 5;
}

public class SomeOtherForm : Form
{
    public void ChangeFirstFormValue(MyFirstForm instance)
    {
        instance.Foo = 10;
    }
}

public class Constants
{
    static const int MIN_SOMETHING = 5;
}

public enum Priorities
{
   High = 10,
   Medium = 5,
   Low = 1
}

...

// When you need to use it:
int priority = (int)Priorities.High;

{
string strQuery = "SELECT Name FROM MyTable";
sqlconn.Open();
daAdapter = new SqlDataAdapter(strQuery, sqlconn);
SqlCommandBuilder scb = new SqlCommandBuilder(daAdapter);
da.Fill(DatatSet1.MyTable);
//Definitions
ParameterField paramfield = new ParameterField();
ParameterFields paramfields = new ParameterFields();
ParameterDiscreteValue discreteval = new ParameterDiscreteValue();
//setting            
paramfield.Name = "Name";
discreteval.Value = DataSet1.MyTable.Columns[0];
paramfield.CurrentValues.Add(discreteval);
paramfields.Add(paramfield);
crystalReportViewer1.ParameterFieldInfo = paramfields;
crystalReportViewer1.ReportSource = crystalreport1;
sqlconn.Close();
}