Question

Please make a Context Free Grammar (CFG) for the regular languages below: The language that is...

Please make a Context Free Grammar (CFG) for the regular languages below:

The language that is in C++ and containing lowercase and upper case letters, and also can have digits, and can also contain the underscore character '_', and it must begin with an underscore or a letter.

Homework Answers

Answer #1

Language containing lowercase and upper case letters, and also can have digits, and can also contain the underscore character '_', and it must begin with an underscore or a letter:

Context Free Grammar :

S-> _A | UA | LA

A-> _A | LA | UA | DA | epsilon

L-> a|b|c|d...........x|y|z

U-> A|B|C|D.............X|Y|Z

D->0|1|2.......8|9

Explanation:  

S-> _A | UA | LA
indicates that it must begin with a underscore(_) , U(uppercase character ) or
L(lowercase letter)

A-> _A | LA | UA | DA | epsilon

indcates that any number of underscores, lowercase characters, uppercase characters
or digits can be added.

and last three productions are used to get the terminal expression.

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