I. Naming rules that must be followed
1. Cannot start with a number or $.
2. Variable names can only be letters (a-z, A-Z), numbers (0-9), underscores (_), (@) or Chinese combination, and cannot contain spaces between them.
3. The variable name cannot contain characters such as? *. - and spaces.
4. Variable names cannot use reserved words of the programming language. For example, lowercase true, false and other reserved words. But uppercase true and false are OK.
II. Classical naming rules
1. Hungarian nomenclature
In this naming method, several characters representing data type are added in front of each variable name. The basic principle is: variable name = attribute + type + object description. For example, if i denotes int, all variable names beginning with i denote int type. s stands for String, and all variables that start with s represent String type variables.
2. Camel nomenclature
As its name implies, it refers to the name of a variable and a function that uses a mixture of uppercase and lowercase letters. Hump nomenclature is similar to Pascal nomenclature, except that the first letter is lowercase, such as userName. It's named because it looks like a hump.
3. Pascal nomenclature
Uppercase of initial, such as UserName.
III. Precautions
1. The character parameter has a single quotation mark '${ace}', while the numeric parameter has no single quotation mark ${ace}. Where adce is the parameter.
2. The reference format of the parameter value is the $ before the parameter, such as $ade.
3. When the template parameter has the same name as the global parameter, the template parameter is used.