$2$ Regular Expressions

Write a regular expression that is similar to the regular expression used to de$-$

scribe hexadecimal numeric constants in $C.$ These are hexadecimal integers,

or hexadecimal floating$-$point values. A hexadecimal integer begins with $0x$

or $0x,$ and may contain the digits $0-9$ and a$/$A$-$f$/$F$.$ A hexadecimal floating$-$

point value has an optional fractional portion and a mandatory exponent

$($beginning with $P$ or $p).$ In hexadecimal, there may be digits to the left of

the dot, the right of the dot, or both, and the exponent itself is given in

decimal, with an optional leading $+$ or $-$ sign. An integer may end with an

optional U or u $($indicating "unsigned"$),$ and$/$or L or l $($indicating "long"$)$

or LL or ll $($indicating "long long"$).$ A floating$-$point value may end with