c# - About Encapsulation : properties -

case :

class example {    private int roll;    public int roll    {        {             return roll;         }        set{            if (value > 0)            { roll = value; }           }    }    //public example()    //{    //    roll = 500;    //}  }  class practice_4 {     static void main(string[] args)     {         example abc = new example();         console.writeline(abc.roll = -1);         console.readline();      } } 

output : -1

i have set business logic not contain illegal value , gives me default value "0"..

case ii:

class example {    private byte roll;    public byte roll    {        {             return roll;         }        set{            if (value > 0)            { roll = value; }           }    }    //public example()    //{    //    roll = 500;    //}  }  class practice_4 {     static void main(string[] args)     {         example abc = new example();         console.writeline(abc.roll = -1);         console.readline();      } } 

above code displaying compile time error change valuetype int byte

error: constant value -1 cannot converted byte ...

what console.writeline method ?

it's because assigment expression returns value being assigned -1 in case. doesn't return abc.roll, can verify outputting property value after assignment:

console.writeline(abc.roll = -1); //-1 console.writeline(abc.roll); //0 

so abc.roll never changes cause of validation logic in setter method.