Usage of get and set in c #

Generally, object-oriented programming languages require that member variables cannot be directly exposed to external access, as follows:
Public class
{
Public int Age; // This is not good. Some programmers may assign-1 to Age later.
}
In order to prevent random value assignment, C # designs an attribute mechanism, which requires that the member variables be set to private and the read/write of member variables be controlled through attributes, as shown below:
Public class B
{
Private int age; // private member variable
Public int Age // age attribute
{
Get {return age;} // Reader
Set {// writer
If (value> 0)
Age = value; // value indicates the value to be written.
}
}
}
In this way, the Age is blocked in front of the age like a security guard. To access the age, you must use the Age permission as follows:
B B = new B ();
B. Age =-1; // This is not feasible.-1 is brought into value, value <0, and judgment is not true.
B. Age = 10; // This is feasible