Implimenting Is Functionality in c#

Question

Can we do IS functionality without using Is keyword as well as GetType and typeof functions. Here i am specific about the heirarchy need to be given by the Is functionality

Hemalatha Sunnapu · Answer

Thank you jaish

Jaish Mathews · Answer

OK. Below are the standards to use in your scenario. Always use "is" operator whenever comparing types/class. Because == operator will fail for derived classes and many other scenarios Never ever use string conversion and string comaprison for comparing types. Your expected types comparison can be achieved by merely using "is" Below is your modified code and I see the expected results too as per your code comments. Identify the commented and added code sections. You don't need a custom "is" implementation. static void Main( string [] args) { Student studentObject = new Student(); Employee employeObject = new Employee(); Teacher teacherObject = new Teacher(); ////String teacherValue = Convert.ToString(teacherObject); ////String studentValue = Convert.ToString(studentObject); ////String employeValue = Convert.ToString(employeObject); // Is operator Console.WriteLine( " Is Functionality 
" ); // Check Employee employeObject is Student Type // bool isStudent = (employeValue == studentValue); bool isStudent = employeObject is Student; Console.WriteLine( "employeObject is a Student type : {0}" , isStudent + "
" ); // Check studentObjectj is Student Type //isStudent = (studentValue == studentValue); isStudent = studentObject is Student; Console.WriteLine( "studentObject is a Student type : {0}" , isStudent + "
" ); // Check teacherObject is Student Type //isStudent = (teacherValue == studentValue); isStudent = teacherObject is Student; Console.WriteLine( "teacherObject is a Student type : {0}" , isStudent + "
" ); // Check null object Type studentObject = null ; //string value1 = Convert.ToString(studentObject); // isStudent = (studentValue == value1); isStudent = studentObject is Student; Console.WriteLine( "studentObject(null) is a Student type : {0}" , isStudent + "
" ); Console.Read(); ; } class Student { //public override string ToString() //{ return "Student"; } } class Teacher { } class Employee : Student { }

Hemalatha Sunnapu · Answer

Hello All, Here is my code.. using System; namespace IsAndAsFunctionality { class Student { public override string ToString() { return "Student" ; } } class Teacher { } class Employee : Student { static void Main( string [] args) { Student studentObject = new Student(); Employee employeObject = new Employee(); Teacher teacherObject = new Teacher(); String teacherValue = Convert.ToString(teacherObject); String studentValue = Convert.ToString(studentObject); String employeValue = Convert.ToString(employeObject); // Is operator Console.WriteLine( " Is Functionality 
" ); // Check Employee employeObject is Student Type bool isStudent = (employeValue == studentValue); Console.WriteLine( "employeObject is a Student type : {0}" , isStudent+ "
" ); // Check studentObjectj is Student Type isStudent = (studentValue == studentValue); Console.WriteLine( "studentObject is a Student type : {0}" , isStudent + "
" ); // Check teacherObject is Student Type isStudent = (teacherValue == studentValue); Console.WriteLine( "teacherObject is a Student type : {0}" , isStudent + "
" ); // Check null object Type studentObject = null ; string value1 = Convert.ToString(studentObject); isStudent = (studentValue == value1); Console.WriteLine( "studentObject(null) is a Student type : {0}" , isStudent + "
" ); Console.Read(); } } }

Jaish Mathews · Answer

Ref. to your code, "==" and "is" won't give same results for all cases. So this is not a problem, but expected bahaviour. Probably so far not getting what you need, especially what is compelling you to not use built-in functionality and write the same by your own.

Sreekanth Reddy · Answer

Can you please provide your isStudent() method related coding part ?

Hemalatha Sunnapu · Answer

Hi sreekanth, I ahve implemented Is functionality ,everything is fine but the onlu probelm is : In inhertinace Example : bool isStudent (Empobj is Student);//returns true as employe id derived // from student isStudent (stuobj is Employe); //retuns false /* IN MY CODE*/ bool isStudent (Empobj ==Student);//returns true as employe id derived // from student isStudent (stuobj is Employe); //retuning true(this is probelm) I have wrote function (logic)to get that.Can anyone help me out.

Sreekanth Reddy · Answer

The thing that what I can speak is: Just imagine "is" also behaving as a logical operator "==". Behaves as same I feel. For Ex : if we try as like below : if("abc"=="def") // Correct doesnt throw error. if("abc"==123) // Throws error. Just think how it's possible ? This logic has already written by microsoft and simply provided us operator (==) to compare. In the same way the "is" too working I hope.

Hemalatha Sunnapu · Answer

Hello Jaish , Thanks for your response , i just wanted to do Is functionality with a logic instead of Is Keyword

Hemalatha Sunnapu · Answer

Yes, i have tried this and even i got the answer, i want to do without built in functions

Hemalatha Sunnapu · Answer

Yes, i have tried this and even i got the answer, i want to do without built in functions

Sreekanth Reddy · Answer

Generally "is" keyword is used to compare the objects. So, I'm not sure.. But try with equilizing the objects(Ex: GetType(obj1) == GetType(obj2)).

Hemalatha Sunnapu · Answer

Yes i knew that, but what Iam trying to know is the "logic" of that keyword

Sreekanth Reddy · Answer

As "is" is a keyword, The internal functionality is going to handled by the CLR. We cant even find the "Go to definition" too.