----------
    public class ItemField
    {
        // Base on SQL Server field elements.
        public string sName;
        public string sDescription;
        public string sRemark;
        public string sDataType;
        public int iMaxLength;
        public int iPrecision;
        public int iScale;
        public Boolean bIsNullable;
        public Boolean bIsAssemblyType;
        public Boolean bIsUserDefined;
        public int iPKeyOrdinal; // (>=1) = a Primary key field.

        public override string ToString()
        {
            return string.Format("Name={0}, Description={1}, Remark={2}, DataType={3}, MaxLength={4}, Precision={5}, Scale={6}, IsAssemblyType={7}, IsNullable={8}, IsUserDefined={9}.",
                sName, sDescription, sRemark, sDataType, iMaxLength.ToString(), iPrecision.ToString(), iScale.ToString(), bIsAssemblyType.ToString(), bIsNullable.ToString(), bIsUserDefined.ToString());
        }

----------
在這個範例中， Square 類別 (Class) 必須提供 Area 的覆寫實作，因為 Area 是繼承自抽象的 ShapesClass

abstract class ShapesClass
{
    abstract public int Area();
}
class Square : ShapesClass
{
    int side = 0;

    public Square(int n)
    {
        side = n;
    }
    // Area method is required to avoid
    // a compile-time error.
    public override int Area()
    {
        return side * side;
    }

    static void Main() 
    {
        Square sq = new Square(12);
        Console.WriteLine("Area of the square = {0}", sq.Area());
    }

    interface I
    {
        void M();
    }
    abstract class C : I
    {
        public abstract void M();
    }

}
// Output: Area of the square = 144


----------
這個範例會定義名為 Employee 的基底類別，以及名為 SalesEmployee 的衍生類別。 
SalesEmployee 類別包含額外的屬性 salesbonus，並會覆寫 CalculatePay 以便將該方法列入考量。

class TestOverride
{
    public class Employee
    {
        public string name;

        // Basepay is defined as protected, so that it may be 
        // accessed only by this class and derrived classes.
        protected decimal basepay;

        // Constructor to set the name and basepay values.
        public Employee(string name, decimal basepay)
        {
            this.name = name;
            this.basepay = basepay;
        }

        // Declared virtual so it can be overridden.
        public virtual decimal CalculatePay()
        {
            return basepay;
        }
    }

    // Derive a new class from Employee.
    public class SalesEmployee : Employee
    {
        // New field that will affect the base pay.
        private decimal salesbonus;

        // The constructor calls the base-class version, and
        // initializes the salesbonus field.
        public SalesEmployee(string name, decimal basepay, 
                  decimal salesbonus) : base(name, basepay)
        {
            this.salesbonus = salesbonus;
        }

        // Override the CalculatePay method 
        // to take bonus into account.
        public override decimal CalculatePay()
        {
            return basepay + salesbonus;
        }
    }

    static void Main()
    {
        // Create some new employees.
        SalesEmployee employee1 = new SalesEmployee("Alice", 
                      1000, 500);
        Employee employee2 = new Employee("Bob", 1200);

        Console.WriteLine("Employee4 " + employee1.name + 
                  " earned: " + employee1.CalculatePay());
        Console.WriteLine("Employee4 " + employee2.name + 
                  " earned: " + employee2.CalculatePay());
    }
}
/*
    Output:
    Employee4 Alice earned: 1500
    Employee4 Bob earned: 1200
*/

----------


The override modifier is required to extend or modify the abstract or virtual implementation of an inherited method, property, indexer, or event.

In this example, the class Square must provide an overridden implementation of Area because Area is inherited from the abstract ShapesClass:



abstract class ShapesClass
{
    abstract public int Area();
}

class Square : ShapesClass
{
    int x, y;
    // Because ShapesClass.Area is abstract, failing to override
    // the Area method would result in a compilation error.
    public override int Area()
    {
        return x * y;
    }
}