Variable definition and use

Overview of variables ：

         Definition of variables ： While the program is running , The amount of value that can change .

         Variables are essentially a small area of memory .

  Variable The definition of ：    

          Variables are defined by variable names , data type , The variable value consists of three parts .

         So the format is ： data type     Variable name   = A variable's value ：

         for example    int a = 3;

Use of variables ：

        Modify the format ： Variable name = A variable's value

public class variable{
    public static void main (String []args){
    // Define a variable 
    int a = 1:
    // Output 
    System.out.println(a);
    // Modify variables 
    a =23;
    // Once again, the output 
    System.out.println(a);
    }
}

This is the process of defining and modifying variables .

matters needing attention ：

        1. The name cannot be repeated

        2. You can't use variables without assignment

        3.long When a type is defined, it should be followed by an uppercase L

        4.float Type to prevent incompatibility , So add... After it F