Early ror learning abstract-Ruby naming rules

Ruby and Java and C ++ have different naming rules for constants, variables, method names, class names, and module names, ruby uses the first letter of a name to differentiate its usage.

1. Local variable: Start with a lowercase letter, for example, Fred anobject _ x three_two_one.

2. instance variable: starts with an @, for example, @ name _ @ size

3. Class variable: starts with two, for example, @ name _ @ size.

4. Constant: start with the first letter.

5. Class Name and module name: a constant.

6. global variables: start with $, for example, $ Params $ program $! $ _ $-A $ -.