The simplest type of expression is the constant, which always has the same value. There are three types of constants: numeric, string, and regular expression.
Each is used in the appropriate context when you need a data value that isn’t going to change. Numeric constants can have different forms, but are stored identically internally.
|• Scalar Constants:||Numeric and string constants.|
|• Nondecimal-numbers:||What are octal and hex numbers.|
|• Regexp Constants:||Regular Expression constants.|