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C# .Net 3.5 使用具有不同返回类型的重载索引器

发布于 2024-08-18 18:13:06 字数 3114 浏览 9 评论 0原文

我有一个父类，它本质上是一个美化的列表。它由多个子类扩展以实现各种功能。

public class HierarchialItemList<ItemType> : IEnumerable<ItemType>
    {
        public ItemType this[String itemCode]
        {
            get
            {
                foreach (IHierarchialItem curItem in hierarchialItems)
                {
                    if (curItem.Code.Equals(itemCode, StringComparison.CurrentCultureIgnoreCase))
                    {
                        return ((ItemType)curItem);
                    }
                }
                return (default(ItemType));
            }
        }
        public ItemType this[Int32 index]
        {
            get
            {
                return (hierarchialItems[index]);
            }
        }
 }

public class DatabaseList : HierarchialItemList<Database>
{
  public DatabaseList this[CommonDatabaseType typeToFilter]
    {
        get
        {
            DatabaseList returnList = new DatabaseList();
            foreach(Database curDatabase in this)
            {
                if (curDatabase.DatabaseType.Equals(typeToFilter))
                {
                    returnList.Add(curDatabase);
                }
            }
            return (returnList);
        }
    }

    public DatabaseList this[Environments.RMSEnvironment environmentToFilter]
    {
        get
        {
            DatabaseList returnList = new DatabaseList();
            foreach(Database curDatabase in this)
            {
                if (curDatabase.ParentEnvironment.Equals(environmentToFilter))
                {
                    returnList.Add(curDatabase);
                }
            }
            return (returnList);
        }
    }


}

问题在于 C# 认为：

Database testDatabase = sampleDatabaseList[0];

是一个错误，并且索引器应该返回 DatabaseList，而不是数据库。你我都知道那是假的。有什么解决方法吗？或者所有索引器都必须具有相同的返回类型吗？

编辑：我刚刚发现这是因为使用枚举作为索引器，它内部是一个整数。不过，有什么方法可以同时使用枚举和整数吗？

编辑2：根据要求，这里有一些可编译的测试代码，它演示了该问题。

using System;
using System.Collections.Generic;

namespace CSQT
{
    class A<T>
    {
        List<T> temp;

        public A()
        {
            temp = new List<T>();
        }

        public void AddItem(T itemToAdd)
        {
            temp.Add(itemToAdd);
        }

    public T this[String code]
    {
        get { return (temp[0]); }

    }

    public T this[Int32 index]
    {
        get { return (temp[index]); }

    }
}

class B : A<String>
{
    public B()
        : base()
    {
    }

    public B this[BTypes testType]
    {
        get
        {
            return (this);
        }
    }
}

enum BTypes { TEMP1, TEMP2 };

class C
{
    public C()
    {
        B temp = new B();

        //Compile error: Cannot implicitly convert type 'CSQT.B' to 'string'
        String temp2 = temp[0];

        //Compile error: Cannot convert type 'CSQT.B' to 'string'
        String temp3 = (String)temp[0];

        //This compiles and runs but instead of going to A.this[int32], it goes to B.this[BTypes testType]
        B temp4 = temp[0];
    }
}
}
原文

I have a parent class which is essentially a glorified list. It's extended by several subclasses for various functionalities.

public class HierarchialItemList<ItemType> : IEnumerable<ItemType>
    {
        public ItemType this[String itemCode]
        {
            get
            {
                foreach (IHierarchialItem curItem in hierarchialItems)
                {
                    if (curItem.Code.Equals(itemCode, StringComparison.CurrentCultureIgnoreCase))
                    {
                        return ((ItemType)curItem);
                    }
                }
                return (default(ItemType));
            }
        }
        public ItemType this[Int32 index]
        {
            get
            {
                return (hierarchialItems[index]);
            }
        }
 }

public class DatabaseList : HierarchialItemList<Database>
{
  public DatabaseList this[CommonDatabaseType typeToFilter]
    {
        get
        {
            DatabaseList returnList = new DatabaseList();
            foreach(Database curDatabase in this)
            {
                if (curDatabase.DatabaseType.Equals(typeToFilter))
                {
                    returnList.Add(curDatabase);
                }
            }
            return (returnList);
        }
    }

    public DatabaseList this[Environments.RMSEnvironment environmentToFilter]
    {
        get
        {
            DatabaseList returnList = new DatabaseList();
            foreach(Database curDatabase in this)
            {
                if (curDatabase.ParentEnvironment.Equals(environmentToFilter))
                {
                    returnList.Add(curDatabase);
                }
            }
            return (returnList);
        }
    }


}

The problem is that C# thinks that this:

Database testDatabase = sampleDatabaseList[0];

Is an error and that the indexer should be returning a DatabaseList, not a Database. You and I both know that's false. Any workarounds or do all indexers have to have the same return type?

Edit: I just figured out that it's because of using an enumeration as an indexer which is internally an integer. Still, any way to use both an enumeration and an integer?

Edit 2: As requested, here is some compiliable test code which demonstrates the problem.

using System;
using System.Collections.Generic;

namespace CSQT
{
    class A<T>
    {
        List<T> temp;

        public A()
        {
            temp = new List<T>();
        }

        public void AddItem(T itemToAdd)
        {
            temp.Add(itemToAdd);
        }

    public T this[String code]
    {
        get { return (temp[0]); }

    }

    public T this[Int32 index]
    {
        get { return (temp[index]); }

    }
}

class B : A<String>
{
    public B()
        : base()
    {
    }

    public B this[BTypes testType]
    {
        get
        {
            return (this);
        }
    }
}

enum BTypes { TEMP1, TEMP2 };

class C
{
    public C()
    {
        B temp = new B();

        //Compile error: Cannot implicitly convert type 'CSQT.B' to 'string'
        String temp2 = temp[0];

        //Compile error: Cannot convert type 'CSQT.B' to 'string'
        String temp3 = (String)temp[0];

        //This compiles and runs but instead of going to A.this[int32], it goes to B.this[BTypes testType]
        B temp4 = temp[0];
    }
}
}

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评论（5）

ぃ双果 2024-08-25 18:13:06

为什么我们知道这是假的？该行

Database testDatabase = sampleDatabaseList[0];

使用参数 0 调用索引器，该参数是 int 文字，因此，看到 DatabaseList 继承自 HierarchialItemList； 将调用定义的索引器，

public ItemType this[Int32 itemCode] { get; }

该索引器声明返回 ItemType。您还没有告诉我们 ItemType 是什么。我们没有理由知道 ItemType 可以分配给 Database 类型的变量。

索引器不必返回相同的类型。但是，不可能仅根据返回类型进行重载。也就是说，这是合法的

class IndexerTest {
    public int this[int index] {
        get {
            return 0;
        }
    }

    public string this[double index] {
        get {
            return "Hello, success!";
        }
    }
}

这不是

class IndexerTest {
    public int this[int index] {
        get {
            return 0;
        }
    }

    public string this[int index] {
        get {
            return "Hello, fail!";
        }
    }
}

对您的编辑的回应：

编辑：我刚刚发现这是因为使用枚举作为内部是整数的索引器。不过，有什么方法可以同时使用枚举和整数吗？

如果您想调用接受枚举的索引器，请像这样调用它：

sampleDatabaseList[Environments.RMSEnvironment.SomeEnumValue];

Why do we know that to be false? The line

Database testDatabase = sampleDatabaseList[0];

invokes the indexer with the parameter 0 which is a int literal and therefore, seeing that DatabaseList inherits from HierarchialItemList<Database> will invoke the indexer defined by

public ItemType this[Int32 itemCode] { get; }

which is declared to return an ItemType. You haven't told us what ItemType is. We have no reason to know that an ItemType can be assigned to a variable of type Database.

Indexers do not have to return the same type. However, it is not possible to overload solely on the basis of return type. That is, this is legal

class IndexerTest {
    public int this[int index] {
        get {
            return 0;
        }
    }

    public string this[double index] {
        get {
            return "Hello, success!";
        }
    }
}

This is not

class IndexerTest {
    public int this[int index] {
        get {
            return 0;
        }
    }

    public string this[int index] {
        get {
            return "Hello, fail!";
        }
    }
}

Responding to your edit:

Edit: I just figured out that it's because of using an enumeration as an indexer which is internally an integer. Still, any way to use both an enumeration and an integer?

If you want to invoke the indexer that accepts an enum, invoke it like so:

sampleDatabaseList[Environments.RMSEnvironment.SomeEnumValue];
回复 原文
情魔剑神 2024-08-25 18:13:06

这是完全有效的代码。

class SomeClass { }
public class A<T> : IEnumerable<T>
{

    public T this[int index]
    {
        get
        {
            return (this[index]);
        }
    }

    public T this[String index]
    {
        get
        {
            return (this[index]);
        }
    }

}
public class B : A<SomeClass>
{
    public B this[char typeToFilter]
    {
        get
        {
            return new B();
        }
    }
}


        B classList = new B();
        SomeClass test = classList[0];

This is perfectly valid code.

class SomeClass { }
public class A<T> : IEnumerable<T>
{

    public T this[int index]
    {
        get
        {
            return (this[index]);
        }
    }

    public T this[String index]
    {
        get
        {
            return (this[index]);
        }
    }

}
public class B : A<SomeClass>
{
    public B this[char typeToFilter]
    {
        get
        {
            return new B();
        }
    }
}


        B classList = new B();
        SomeClass test = classList[0];
回复 原文
撕心裂肺的伤痛 2024-08-25 18:13:06
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Employee : Person
    {
        string id;
        public string Id
        {
            get { return id; }
            set { id = value; }
        }

        decimal salary;
        public decimal Salary
        {
            get { return salary; }
            set { salary = value; }
        }

        string password;
        public string Password
        {
            set { password = value; }
        }

        int ichk = 1, schk = 1, pchk = 1;


        public Employee()
            : base()
        {
            Id = null;
            Salary = Convert.ToDecimal("0.0");
            Password = null;
        }

        public Employee(string n, char g, DateTime d, string empid, decimal sal, string pwd)
            : base(n, g, d)
        {
            Id = empid;
            Salary = sal;
            Password = pwd;
        }

        public override void Accept()
        {
            base.Accept();
            try
            {
                Console.Write("Enter the EMPID:");
                Id = Console.ReadLine();
                if (string.IsNullOrEmpty(Id) == true)
                {
                    ichk = 0;
                    Console.WriteLine("No ID entered!");
                }

                string salcheck;
                Console.Write("Enter the Salary:");
                salcheck = Console.ReadLine();
                if (string.IsNullOrEmpty(salcheck) == true)
                {
                    schk = 0;
                    Console.WriteLine("Invalid Salary");
                }
                else
                {
                    Salary = Convert.ToDecimal(salcheck);
                    if (Salary < 0)
                    {
                        schk = 0;
                        Console.WriteLine("Invalid Salary");
                    }
                }

                Console.Write("Enter Password:");
                Password = Console.ReadLine();
                if (string.IsNullOrEmpty(password) == true)
                {
                    pchk = 0;
                    Console.WriteLine("Empty Password!");
                }
                else
                {
                    string pwd;
                    int pchk = 0;
                    do
                    {
                        Console.Write("Re-Enter Password:");
                        pwd = Console.ReadLine();
                        if (string.IsNullOrEmpty(pwd) == true || pwd != password)
                            Console.WriteLine("Passwords don't match!");
                        else
                            pchk = 1;
                    } while (pchk == 0);
                }
            }
            catch (Exception e)
            {
                Console.Write(e.Message);
            }

        }


        public override void Print()
        {
            base.Print();

            if (ichk == 1)
            {
                Console.WriteLine("EMPID:{0}", Id);
            }
            else
                Console.WriteLine("No Id!");

            if (schk == 1)
            {
                Console.WriteLine("Salary:{0}", Salary);
            }
            else
                Console.WriteLine("Invalid Salary!");

        }

    }
}

------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Person
    {
        protected string name;
        public string Name
        {
            get { return name; }
            set { name = value; }
        }

        protected char gender;
        public char Gender
        {
            get { return gender; }
            set { gender = value; }
        }

        protected DateTime? dob;
        public DateTime? Dob
        {
            get { return dob; }
            set { dob = value; }
        }

        protected int age;
        public int Age
        {
            get { return age; }
        }

        public Person()
        {
            Name = "Default";
            Gender = 'M';
            Dob = null;
            age = 0;
        }
        public Person(string n, char g, DateTime d)
        {
            Name = n;
            Gender = g;
            Dob = d;
            age = DateTime.Now.Year - Dob.Value.Year;
        }

        int nchk = 1, gchk = 0, dchk = 0;
        string datetimecheck, gendercheck;
        public virtual void Accept()
        {
            try
            {
                Console.Write("Enter the name:");
                Name = Console.ReadLine();
                if (string.IsNullOrEmpty(Name)==true)
                {
                    nchk = 0;
                    Console.WriteLine("No name entered!");
                }

                Console.Write("Enter the Date of birth:");
                datetimecheck = Console.ReadLine();
                if (string.IsNullOrEmpty(datetimecheck) == true)
                {                    
                    dchk = 0;
                    Console.WriteLine("No date entered!");
                }
                else
                {
                    Dob = Convert.ToDateTime(datetimecheck);
                    age = DateTime.Now.Year - Dob.Value.Year;
                    dchk = 1;
                }

                Console.Write("Enter Gender:");
                gendercheck = Console.ReadLine();
                if (gendercheck != "m" && gendercheck != "M" && gendercheck != "f" && gendercheck != "F")
                {
                    gchk = 0;
                    Console.WriteLine("Invalid Gender");
                }
                else
                {
                    gchk = 1;
                    Gender = Convert.ToChar(gendercheck);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }

        }

        public virtual void Print()
        {
            Console.WriteLine("\n\nThe Employee Details are:\n");

            if (nchk == 1)
            {
                Console.WriteLine("Name:{0}", Name);
            }
            else
                Console.WriteLine("No Name!");

            if (gchk == 1)
            {
                Console.WriteLine("Gender:{0}", Gender);
            }
            else
                Console.WriteLine("No Gender!");

            if (dchk == 1)
            {
                Console.WriteLine("Date Of Birth:{0}", Dob);
                Console.WriteLine("Age:{0}", Age);
            }
            else
                Console.WriteLine("No Date Of Birth!");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Employee : Person
    {
        string id;
        public string Id
        {
            get { return id; }
            set { id = value; }
        }

        decimal salary;
        public decimal Salary
        {
            get { return salary; }
            set { salary = value; }
        }

        string password;
        public string Password
        {
            set { password = value; }
        }

        int ichk = 1, schk = 1, pchk = 1;


        public Employee()
            : base()
        {
            Id = null;
            Salary = Convert.ToDecimal("0.0");
            Password = null;
        }

        public Employee(string n, char g, DateTime d, string empid, decimal sal, string pwd)
            : base(n, g, d)
        {
            Id = empid;
            Salary = sal;
            Password = pwd;
        }

        public override void Accept()
        {
            base.Accept();
            try
            {
                Console.Write("Enter the EMPID:");
                Id = Console.ReadLine();
                if (string.IsNullOrEmpty(Id) == true)
                {
                    ichk = 0;
                    Console.WriteLine("No ID entered!");
                }

                string salcheck;
                Console.Write("Enter the Salary:");
                salcheck = Console.ReadLine();
                if (string.IsNullOrEmpty(salcheck) == true)
                {
                    schk = 0;
                    Console.WriteLine("Invalid Salary");
                }
                else
                {
                    Salary = Convert.ToDecimal(salcheck);
                    if (Salary < 0)
                    {
                        schk = 0;
                        Console.WriteLine("Invalid Salary");
                    }
                }

                Console.Write("Enter Password:");
                Password = Console.ReadLine();
                if (string.IsNullOrEmpty(password) == true)
                {
                    pchk = 0;
                    Console.WriteLine("Empty Password!");
                }
                else
                {
                    string pwd;
                    int pchk = 0;
                    do
                    {
                        Console.Write("Re-Enter Password:");
                        pwd = Console.ReadLine();
                        if (string.IsNullOrEmpty(pwd) == true || pwd != password)
                            Console.WriteLine("Passwords don't match!");
                        else
                            pchk = 1;
                    } while (pchk == 0);
                }
            }
            catch (Exception e)
            {
                Console.Write(e.Message);
            }

        }


        public override void Print()
        {
            base.Print();

            if (ichk == 1)
            {
                Console.WriteLine("EMPID:{0}", Id);
            }
            else
                Console.WriteLine("No Id!");

            if (schk == 1)
            {
                Console.WriteLine("Salary:{0}", Salary);
            }
            else
                Console.WriteLine("Invalid Salary!");

        }

    }
}

------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Person
    {
        protected string name;
        public string Name
        {
            get { return name; }
            set { name = value; }
        }

        protected char gender;
        public char Gender
        {
            get { return gender; }
            set { gender = value; }
        }

        protected DateTime? dob;
        public DateTime? Dob
        {
            get { return dob; }
            set { dob = value; }
        }

        protected int age;
        public int Age
        {
            get { return age; }
        }

        public Person()
        {
            Name = "Default";
            Gender = 'M';
            Dob = null;
            age = 0;
        }
        public Person(string n, char g, DateTime d)
        {
            Name = n;
            Gender = g;
            Dob = d;
            age = DateTime.Now.Year - Dob.Value.Year;
        }

        int nchk = 1, gchk = 0, dchk = 0;
        string datetimecheck, gendercheck;
        public virtual void Accept()
        {
            try
            {
                Console.Write("Enter the name:");
                Name = Console.ReadLine();
                if (string.IsNullOrEmpty(Name)==true)
                {
                    nchk = 0;
                    Console.WriteLine("No name entered!");
                }

                Console.Write("Enter the Date of birth:");
                datetimecheck = Console.ReadLine();
                if (string.IsNullOrEmpty(datetimecheck) == true)
                {                    
                    dchk = 0;
                    Console.WriteLine("No date entered!");
                }
                else
                {
                    Dob = Convert.ToDateTime(datetimecheck);
                    age = DateTime.Now.Year - Dob.Value.Year;
                    dchk = 1;
                }

                Console.Write("Enter Gender:");
                gendercheck = Console.ReadLine();
                if (gendercheck != "m" && gendercheck != "M" && gendercheck != "f" && gendercheck != "F")
                {
                    gchk = 0;
                    Console.WriteLine("Invalid Gender");
                }
                else
                {
                    gchk = 1;
                    Gender = Convert.ToChar(gendercheck);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }

        }

        public virtual void Print()
        {
            Console.WriteLine("\n\nThe Employee Details are:\n");

            if (nchk == 1)
            {
                Console.WriteLine("Name:{0}", Name);
            }
            else
                Console.WriteLine("No Name!");

            if (gchk == 1)
            {
                Console.WriteLine("Gender:{0}", Gender);
            }
            else
                Console.WriteLine("No Gender!");

            if (dchk == 1)
            {
                Console.WriteLine("Date Of Birth:{0}", Dob);
                Console.WriteLine("Age:{0}", Age);
            }
            else
                Console.WriteLine("No Date Of Birth!");
        }
    }
}
回复 原文
诗酒趁年少 2024-08-25 18:13:06

添加必要的类和属性来编译代码示例后，我可以毫无问题地运行此语句：

Database testDatabase = sampleDatabaseList[0];

如果您收到以下错误：< code>sampleDatabaseList[0] 返回 DatabaseList，请提供包含语句 DatabaseList testDatabase = sampleDatabaseList[0]; 的可编译代码示例

After adding the necessary classes and attributes to get your code sample to compile, I was able to run this statement with no issues:

Database testDatabase = sampleDatabaseList[0];

If you're getting an error that sampleDatabaseList[0] returns a DatabaseList, please provide a compilable code sample that contains the statement DatabaseList testDatabase = sampleDatabaseList[0];

回复 原文
风为裳 2024-08-25 18:13:06
---TRIGGER--

CREATE TRIGGER TriggerTest
ON EMP
AFTER INSERT, UPDATE, DELETE 

AS
BEGIN

declare @day varchar(10)
select @day=datename(dw,getdate())

declare @hour int
Select @hour=convert(varchar(2),getdate(),114)

if ( @hour < 9 OR @hour > 13 OR @day = 'Saturday' OR @day = 'Sunday')
BEGIN

if UPDATE(EMPID)
RAISERROR ('Error!',1,16)
rollback tran

END

END

Insert into EMP values(1003,'A','A')

drop trigger TriggerTest

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Employee:Person
    {
        string id;
        public string Id
        {
            get { return id; }
            set { id = value; }
        }

        decimal salary;
        public decimal Salary
        {
            get { return salary; }
            set { salary = value; }
        }

        string password;
        public string Password
        {
            set { password = value; }
        }

        int ichk = 1, schk = 1, pchk = 1;


        public Employee()
            : base()
        {
            Id = null;
            Salary = Convert.ToDecimal("0.0");
            Password = null;
        }

        public Employee(string n, char g, DateTime d, string empid, decimal sal, string pwd)
            : base(n, g, d)
        {
            Id = empid;
            Salary = sal;
            Password = pwd;
        }

        public override void Accept()
        {
            base.Accept();
            try
            {
                Console.Write("Enter the EMPID:");
                Id = Console.ReadLine();
                if (Id == null)
                {
                    ichk = 0;
                    Console.WriteLine("No ID entered!");
                }

                Console.Write("Enter the Salary:");
                Salary = Convert.ToDecimal(Console.ReadLine());
                if (Salary < 0)
                {
                    schk = 0;
                    Console.WriteLine("Invalid Salary");
                }

                Console.Write("Enter Password:");
                Password = Convert.ToString(Console.ReadLine());
                if (password == null)
                {
                    pchk = 0;
                    Console.WriteLine("Empty Password!");
                }
            }
            catch (Exception e)
            {
                Console.Write(e.Message);
            }

        }


        public override void Print()
        {
            base.Print(); 

            if (ichk == 1)
            {
                Console.WriteLine("EMPID:{0}", Id);
            }
            else
                Console.WriteLine("No Id!");

            if (schk == 1)
            {
                Console.WriteLine("Salary:{0}", Salary);
            }
            else
                Console.WriteLine("Invalid Salary!");

        }

    }
}



-----PERSON-----
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Person
    {
        protected string name;
        public string Name
        {
            get { return name; }
            set { name = value; }
        }

        protected char gender;
        public char Gender
        {
            get { return gender; }
            set { gender = value; }
        }

        protected DateTime dob;
        public DateTime Dob
        {
            get { return dob; }
            set { dob = value; }
        }

        protected int age;
        public int Age
        {
            get { return age; }            
        }

        public Person()
        {
            Name = "Default";
            Gender = 'M';
            Dob = Convert.ToDateTime("09 / 12 / 1990");
            age = 0;
        }
        public Person(string n, char g, DateTime d)
        {
            Name = n;
            Gender = g;
            Dob = d;
            age = DateTime.Now.Year - Dob.Year;
        }

        int nchk = 1, gchk = 1, dchk = 1;
        public virtual void Accept()
        {
            try
            {
                Console.Write("Enter the name:");
                Name = Console.ReadLine();
                if(Name == null)
                {
                    nchk = 0;
                    Console.WriteLine("No name entered!");
                }

                Console.Write("Enter the Date of birth:");
                Dob = Convert.ToDateTime(Console.ReadLine());
                if (Dob == null)
                {
                    dchk = 0;
                    Console.WriteLine("No date entered!");
                }
                else
                {
                    age = DateTime.Now.Year - Dob.Year;
                }

                Console.Write("Enter Gender:");
                Gender = Convert.ToChar(Console.ReadLine());
                if (Gender != 'm' && Gender != 'M' && Gender != 'F' && Gender != 'f')
                {
                    gchk = 0;
                    Console.WriteLine("Invalid Gender");                   
                }
            }
            catch (Exception e)
            {
                Console.Write(e.Message);
            }

        }

        public virtual void Print()
        {
            Console.WriteLine("\n\nThe Employee Details are:\n");

            if (nchk == 1)
            {
                Console.WriteLine("Name:{0}", Name);
            }
            else
                Console.WriteLine("No Name!");

            if (gchk == 1)
            {
                Console.WriteLine("Gender:{0}", Gender);
            }
            else
                Console.WriteLine("No Gender!");

            if (dchk == 1)
            {
                Console.WriteLine("Date Of Birth:{0}", Dob);
                Console.WriteLine("Age:{0}", Age);
            }
            else
                Console.WriteLine("No Date Of Birth!");
        }
    }
}

---TRIGGER--

CREATE TRIGGER TriggerTest
ON EMP
AFTER INSERT, UPDATE, DELETE 

AS
BEGIN

declare @day varchar(10)
select @day=datename(dw,getdate())

declare @hour int
Select @hour=convert(varchar(2),getdate(),114)

if ( @hour < 9 OR @hour > 13 OR @day = 'Saturday' OR @day = 'Sunday')
BEGIN

if UPDATE(EMPID)
RAISERROR ('Error!',1,16)
rollback tran

END

END

Insert into EMP values(1003,'A','A')

drop trigger TriggerTest

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Employee:Person
    {
        string id;
        public string Id
        {
            get { return id; }
            set { id = value; }
        }

        decimal salary;
        public decimal Salary
        {
            get { return salary; }
            set { salary = value; }
        }

        string password;
        public string Password
        {
            set { password = value; }
        }

        int ichk = 1, schk = 1, pchk = 1;


        public Employee()
            : base()
        {
            Id = null;
            Salary = Convert.ToDecimal("0.0");
            Password = null;
        }

        public Employee(string n, char g, DateTime d, string empid, decimal sal, string pwd)
            : base(n, g, d)
        {
            Id = empid;
            Salary = sal;
            Password = pwd;
        }

        public override void Accept()
        {
            base.Accept();
            try
            {
                Console.Write("Enter the EMPID:");
                Id = Console.ReadLine();
                if (Id == null)
                {
                    ichk = 0;
                    Console.WriteLine("No ID entered!");
                }

                Console.Write("Enter the Salary:");
                Salary = Convert.ToDecimal(Console.ReadLine());
                if (Salary < 0)
                {
                    schk = 0;
                    Console.WriteLine("Invalid Salary");
                }

                Console.Write("Enter Password:");
                Password = Convert.ToString(Console.ReadLine());
                if (password == null)
                {
                    pchk = 0;
                    Console.WriteLine("Empty Password!");
                }
            }
            catch (Exception e)
            {
                Console.Write(e.Message);
            }

        }


        public override void Print()
        {
            base.Print(); 

            if (ichk == 1)
            {
                Console.WriteLine("EMPID:{0}", Id);
            }
            else
                Console.WriteLine("No Id!");

            if (schk == 1)
            {
                Console.WriteLine("Salary:{0}", Salary);
            }
            else
                Console.WriteLine("Invalid Salary!");

        }

    }
}



-----PERSON-----
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestNameSpace
{
    public class Person
    {
        protected string name;
        public string Name
        {
            get { return name; }
            set { name = value; }
        }

        protected char gender;
        public char Gender
        {
            get { return gender; }
            set { gender = value; }
        }

        protected DateTime dob;
        public DateTime Dob
        {
            get { return dob; }
            set { dob = value; }
        }

        protected int age;
        public int Age
        {
            get { return age; }            
        }

        public Person()
        {
            Name = "Default";
            Gender = 'M';
            Dob = Convert.ToDateTime("09 / 12 / 1990");
            age = 0;
        }
        public Person(string n, char g, DateTime d)
        {
            Name = n;
            Gender = g;
            Dob = d;
            age = DateTime.Now.Year - Dob.Year;
        }

        int nchk = 1, gchk = 1, dchk = 1;
        public virtual void Accept()
        {
            try
            {
                Console.Write("Enter the name:");
                Name = Console.ReadLine();
                if(Name == null)
                {
                    nchk = 0;
                    Console.WriteLine("No name entered!");
                }

                Console.Write("Enter the Date of birth:");
                Dob = Convert.ToDateTime(Console.ReadLine());
                if (Dob == null)
                {
                    dchk = 0;
                    Console.WriteLine("No date entered!");
                }
                else
                {
                    age = DateTime.Now.Year - Dob.Year;
                }

                Console.Write("Enter Gender:");
                Gender = Convert.ToChar(Console.ReadLine());
                if (Gender != 'm' && Gender != 'M' && Gender != 'F' && Gender != 'f')
                {
                    gchk = 0;
                    Console.WriteLine("Invalid Gender");                   
                }
            }
            catch (Exception e)
            {
                Console.Write(e.Message);
            }

        }

        public virtual void Print()
        {
            Console.WriteLine("\n\nThe Employee Details are:\n");

            if (nchk == 1)
            {
                Console.WriteLine("Name:{0}", Name);
            }
            else
                Console.WriteLine("No Name!");

            if (gchk == 1)
            {
                Console.WriteLine("Gender:{0}", Gender);
            }
            else
                Console.WriteLine("No Gender!");

            if (dchk == 1)
            {
                Console.WriteLine("Date Of Birth:{0}", Dob);
                Console.WriteLine("Age:{0}", Age);
            }
            else
                Console.WriteLine("No Date Of Birth!");
        }
    }
}
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