Exercise $3\mathrm{.}3\mathrm{.}1$: Consult the language reference manuals to determine $(i)$ the sets of characters that form the input alphabet $($excluding those that may only appear in character strings or comments$),($ii$)$ the lexical form of numerical constants, and $($iii$)$ the lexical form of identifiers, for each of the following languages: $($a$)$ C $($b$)$ C$++($c$)$ C# $($d$)$ Fortran $($e$)$ Java $($f$)$ Lisp $($g$)$ SQL$.$

$!$ Exercise $3\mathrm{.}3\mathrm{.}2$: Describe the languages denoted by the following regular expressions:

a$)(b|).$

b$)((a|)).$

c$)(b(b(b|)|)|).$

d$)a^{**}b{a}^{**}b{a}^{**}b{a}^{**}.$

$!!$ e$)(bb(ba(bb(ba((bb|)|)|)|))|).$

Exercise $3\mathrm{.}3\mathrm{.}3$ : In a string of length $n,$ how many of the following are there?

a$)$ Prefixes.

b$)$ Suffixes.

c$)$ Proper prefixes.

$!$d$)$ Substrings.

$!$ e$)$ Subsequences.