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    BNF grammar and parse tree

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    1. Write a BNF grammar that describes the structure of a nonterminal called <number>. Assume that <number> contains an optional + sign followed by exactly 2 decimal digits, the first of which cannot be a 0. Thus 23, +91, and +40 are legal, but 9, +01, and 123 are not.

    Using this grammar, show a parse tree for the value +90.

    2. Write a BNF grammar for identifiers that consist of an arbitrarily long string of letters and digits, the first one of which must be a letter.

    Using this grammar, show a parse tree for the identifier AB5C8.

    © BrainMass Inc. brainmass.com October 9, 2019, 9:36 pm ad1c9bdddf
    https://brainmass.com/computer-science/trees/bnf-grammar-parse-tree-191762

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    1. BNF grammar :

    <number> ::= + <nzdigit> <digit> | <nzdigit> <digit>
    <digit> ::= 0 | <nzdigit>
    <nzdigit> ::= 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

    Parse tree for +90 :

    number
    / |
    + |
    nzdigit
    | digit
    9 |
    ...

    Solution Summary

    Answer shows the parse trees (drawn neatly) in text mode.

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