How are static variables defined in a class?

• A. By using the 'instance' keyword
• B. By using the 'local' keyword
• C. By using the 'static' keyword
• D. By using the 'shared' keyword

Answer: (C)

Static variables in a class are defined using the 'static' keyword. When a variable is declared as static, it means that the variable belongs to the class itself rather than to any specific instance of the class. This allows a single copy of the variable to be shared among all instances of the class. As a result, static variables maintain their state across all instances, which can be particularly useful for keeping track of data that is common to all objects, such as a counter for the number of objects created or configuration settings that apply to the entire class.

Using the 'static' keyword is a common practice in object-oriented programming languages like Java, C#, and C++. It defines the variable's lifetime and scope, making it accessible without needing to instantiate a class. Therefore, when working with static variables, it’s important to understand their implications on memory management and accessibility. This is why the option that indicates using the 'static' keyword as the method for defining these types of variables is correct.