I. What are variables?
Quantity: Recording a state of something in the real world
Change: A certain state of things can change.
2. Why use variables
A state in which a computer can record things like a human being.
3. How to use variables
Principle: Define first, quote later
Define the three components of variables first
1Variable name: the only way to access worthwhile
2 = Symbols bind variable-worthy memory addresses to variable names
3 The value of a variable: The data we store is used to represent a state of something.
IV. Naming of variables
Prerequisite: Variable names should have descriptive effects on values
1.Variable names can only be any combination of letters, numbers, or underscores
2.The first character of a variable name cannot be a number
3.System keywords cannot be declared as variables
Naming Style: Hump Body
Pure lowercase letters + underscores