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Today I had a task to create serial number control in WPF application.

The requirements:

1. There are five text box fields;
2. Each text box should allow to enter only 4 symbols;
3. The control should be smart when user copies the whole code to the first text box.

The most common (erroneous) attempt to fix the evident problems from newing up DEPENDENCIES involves a factory of some sort. There are several options when it comes to factories, and I’ll quickly cover each of the following:

■ Concrete Factory
■ Abstract Factory
■ Static Factory

DI helps by enabling loose coupling. Specifically, we gain the benefits listed in the table.

In C#, arguments can be passed to parameters either by value or by reference. It seems to be quite simple and I want to review typical questions according the topic.

I continue the series that explain typical questions on the coder's job interview.

Another primary concept of object-oriented programming is Polymorphism. It allows you to invoke derived class methods through a base class reference during run-time.

When a derived class inherits from a base class, it gains all the methods, fields, properties and events of the base class. To change the data and behavior of a base class, you have two choices: you can replace the base member with a new derived member, or you can override a virtual base member.