Define abstract class and abstract method : Abstract Class « Class « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Class
3. Abstract Class

using System;

abstract class Employee
{
    public Employee(string name, float billingRate)
    {
        this.name = name;
        this.billingRate = billingRate;
    }
    
    virtual public float CalculateCharge(float hours)
    {
        return(hours * billingRate);
    }
    
    abstract public string TypeName();
    
    private string name;
    protected float billingRate;
}

class Manager: Employee
{
    public Manager(string name, float billingRate) : base(name, billingRate)
    {
    }
    
    override public float CalculateCharge(float hours)
    {
        if (hours < 1.0F)
        hours = 1.0F;        // minimum charge.
        return(hours * billingRate);
    }
    
    // This override is required, or an error is generated.
    override public string TypeName()
    {
        return("Manager");
    }
}

class Clerk: Employee
{
    public Clerk(string name, float billingRate) :
    base(name, billingRate)
    {
    }
    
    override public string TypeName()
    {
        return("Clerk");
    }
}
class Test
{
    public static void Main()
    {
        Employee[] earray = new Employee[2];
        earray[0] = new Manager("A", 40.0F);
        earray[1] = new Clerk("C", 45.0F);
        
        Console.WriteLine("{0} charge = {1}",
        earray[0].TypeName(),
        earray[0].CalculateCharge(2F));
        Console.WriteLine("{0} charge = {1}",
        earray[1].TypeName(),
        earray[1].CalculateCharge(0.75F));
    }
}

Manager charge = 80
Clerk charge = 33.75