PLEASE READ CAREFULLY consider the following grammar: ::= + | * | ( ) | ::= a

PLEASE READ CAREFULLY

consider the following grammar:

<E>	::=	<E> + <E> | <E> * <E> | ( <E> ) | <id>
<id>	::=	a | b | . . . | z

1 . State in your own words what kinds of sentences (strings) these productions describe.

2 . Give 3 examples of valid strings, and 3 examples of invalid strings, according to the grammar.

3.     3. Write a lexical analyzer (scanner) program for this BNF in c++.   

This scanner should prompt the user to input a string, then output a list of tokens and lexemes , one per line, from the input string according to the above grammar. If something is “wrong” in the input stream it should output an error message of some kind and abandon the scan.

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