Properties

What is the difference between variable and property?



When we talk about any class or object it has two things – Data and Business logic. When it comes to data we have variables. When it comes to Business logic we have some intermediate results and for that again we have variables. Variables are simply named memory locations where we can store our data or temporary results. Let’s have a small example about variable. public class Customer { publicstring customerName; } . . Customer c=new Customer(); c.customerName= “Sukesh Marla”; Let’s have one more example. public class Customer { publicstring customerName, publicint age; } . . Customer c=new Customer(); c.customerName= “Sukesh Marla”; c.age=55; //Perfect c.age=555; // Ohh!! No, what the hell is this? c.age= -5; //What rubbish. Our data is not protected. It should be validated before it dumped into variable. Now the question is who will do the validation? We have two developers with us now – one who have developed the above class (let’s call him creator) and second who will use this class (let’s call him end developer). If end developer do this validation then, It’s strictly a violation of SOC ( separation of concerns) It will be difficult to reuse the validation logic. So the final decision is to put validation in Customer class itself by its creator. For this we will simply create a function in Customer class which will do the validation and return either true or false. End developer will just call that function before assigning value. Example public class Customer { publicstring customerName, publicint age; publicboolIsValidAge(int _age) { If(_age>0 && _age<100) { returntrue; } else { return false; } } } . . Customer c=new Customer(); c.customerName=”Sukesh Marla”; intTempAge=int.parse(TxtAge.Text); if(c.IsValidAge(TempAge)) { c.Age=TempAge; } Is there any issue more? Yes, what if end developer fail to forget to call IsValidAge method before assigning value. Ultimate solution – Property Our data should get validated as soon as someone try to put values to it and for that we have properties in C#. It is an encapsulation over our normal variables providing get and set accessory. Get will be executed when someone try to retrieve the value of it and set will be executed when someone try to modify the value of it. Thus it makes our data protected. Example : public class Customer { public string customerName, privateint _age; publicint Age { get { Return _age; } set { If(_age>0 && _age<100) { _age=Value; } else { throw new Exception(“Invalid data”); } } } } . . Customer c=new Customer(); c.customerName=”Sukesh Marla”; intTempAge=int.parse(TxtAge.Text); if(c.IsValidAge(TempAge)) { c.Age=TempAge; }

Sujeet Suman11y ago

Properties combine aspects of both fields and methods. To the user of an object, a property appears to be a field, accessing the property requires the same syntax. To the implementer of a class, a property is one or two code blocks, representing a get accessor and/or a set accessor. The code block for the get accessor is executed when the property is read; the code block for the set accessor is executed when the property is assigned a new value. A property without a set accessor is considered read-only. A property without a get accessor is considered write-only. A property that has both accessors is read-write.

Pankaj Kumar Choudhary11y ago

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Sharad11y ago

Let's understand by considering the below example:

You have a room and a door to enter this room. If you want to check how who is coming in and secure your room, then you should use properties otherwise they won't be any door and every one easily come in w/o any regulation.

class Room {
   public string sectionOne;
   public string sectionTwo;
}

Room r = new Room();
r.sectionOne = "enter";

People is getting in to sectionOne pretty easily, there wasn't any checking.

Now see with implementing properties:

class Room {
   private string sectionOne;
   private string sectionTwo;

   public string SectionOne {
      get{return sectionOne;
}
set{sectionOne = Check(value);}

}

}

Room r = new Room();
r.SectionOne = "enter";

now you checked the person and know about whether he has something evil with him.

Features of Properties

There are a few reasons to use properties, instead of public fields/methods.

(i) Properties can be virtual.

(ii) You can make the setters for a property private.

(iii) Properties have a 'special' meaning to things that inspect classes at runtime.