If you have a class:
public class Car { public static readonly int Wheels = 4; public static int Count {get;set;} public string Make {get;set;} public string Model {get;set;} public int Year {get;set;} public Car() { Car.Count = Car.Count + 1; } public string SoundOff(){ return String.Format("I am only 1 out of {0} car{1}", Car.Count, (Car.Count > 0 ? "s" : String.Empty)); } }
Then, every time you create a car, the count will increase by one. This is because the Count property belongs to the Car class, and not to ever object you've created.
This is also useful because every car can have knowledge of the Car.Count. So, if you created:
Car sportster = new Car { Make="Porsche", Model="Boxster", Year=2010 }; sportster.SoundOff(); // I am only 1 out of 1 car
You can do other processing and Count will be known to all objects:
Car hybrid = new Car { Make="Toyota", Model="Prius", Year=2010 }; hybrid.SoundOff(); // I am only 1 out of 2 cars sportster.SoundOff(); // I am only 1 out of 2 cars
So, in other words, you should use static when you want something to:
- Be accessible at the class-level so all objects know of it (
Car.Count instead of hybrid.Count) - Represent the class and not the object (
Car.Wheels won't change)
There are other reasons to use static, like Utility classes, extension methods, etc. But this should answer your question about the MSDN wording.
