Question

Research to write down the rule of a variable identifier in the following programming languages and write down the regular grammar for that rule. For example, as elaborated in the class, the rule of a variable identifier in C is "start either by_, or any alphabetic character, and then follow either by_, any alphabetic character, or number", and its regular grammar is: La-zA-Z][a-zA-ZO-9]* a. JavaScript i. Rule: ii. Regular grammar b. PHP i. Rule: ii. Regular grammar: c. Python i. Rule: li. Regular grammar: d. GoLang i. Rule: ii. Regular grammar:

Answer 1

a. Javascript

Rule - variables first character must be a letter, or an underscore (_), or a dollar sign ($).

Regular Grammar - [ _ $ a-z A-Z ][a-z A-Z 0-9]

b. Php

Rule - it include letters, numbers, underscore characters, and other ASCII characters from 127 through 255

Regular Grammar - [ _ a-z A-Z ][a-z A-Z 0-9]

c. Python

Rule - varible starts with a letter A to Z or a to z or an underscore (_) followed by zero or more letters, underscores and digits (0 to 9).

Regular Grammar - [ _ a-z A-Z ][a-z A-Z 0-9]

d. GoLang -

Rule - variables starts with a letter A to Z or a to z , underscores in between or digits (0 to 9).

Regular Grammar - [ a-z A-Z _ ][a-z A-Z 0-9]