Experience Summary-Small D quotations

1. When to define class variables and instance variables?

D: When you use instance variables in the class, you can define the class variables if you find that it is not enough.

Example: Count the total number of students in the class.

 

2. What is the difference between a class method and a class-defined method?

Small D: class method, that is, the method defined in the class that begins with the class name

The difference is:

Method defined in the class: The method must be instantiated first and called using an instance.

Class Method: can be used directly without instantiation.

Example:

ClassSample

{

Define method_1 () # method defined in the class

{

}

Define method_2 () # methods defined in the class

{

}

Sample. method_3 ()#Class Method

{

}

}

Class_1 = sample. New (); # create a class instance

Calss_1.method_1; # Use the method defined in the class

 

Sample. method_3 (); # class method, which can be used directly.