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<H1> 2.4.2 Based Literals</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> [ <A NAME="I1231"></A><A NAME="I1232"></A><A NAME="I1233"></A><A NAME="I1234"></A><A NAME="I1235"></A><A NAME="I1236"></A><A NAME="I1237"></A><A NAME="I1238"></A><A NAME="I1239"></A><A NAME="I1240"></A>A
<FONT FACE="Arial, Helvetica">based_literal</FONT> is a <FONT FACE="Arial, Helvetica">numeric_literal</FONT>
expressed in a form that specifies the base explicitly.] </DIV>
<H4 ALIGN=CENTER>Syntax</H4>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">based_literal<A NAME="I1241"></A>
::= </FONT><BR>
<A NAME="I1242"></A><FONT FACE="Arial, Helvetica">base</FONT> # <A NAME="I1243"></A><FONT FACE="Arial, Helvetica">based_numeral</FONT> [.<A NAME="I1244"></A><FONT FACE="Arial, Helvetica">based_numeral</FONT>] # [<A NAME="I1245"></A><FONT FACE="Arial, Helvetica">exponent</FONT>]</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">base<A NAME="I1246"></A>
::= </FONT><A NAME="I1247"></A><FONT FACE="Arial, Helvetica">numeral</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">based_numeral<A NAME="I1248"></A>
::= </FONT><BR>
<A NAME="I1249"></A><FONT FACE="Arial, Helvetica">extended_digit</FONT> {[<A NAME="I1250"></A><FONT FACE="Arial, Helvetica">underline</FONT>] <A NAME="I1251"></A><FONT FACE="Arial, Helvetica">extended_digit</FONT>}</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">extended_digit<A NAME="I1252"></A>
::= </FONT><A NAME="I1253"></A><FONT FACE="Arial, Helvetica">digit</FONT> | A | B | C | D | E | F</DIV>
<H4 ALIGN=CENTER>Legality Rules</H4>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="Normal"> <A NAME="I1254"></A>The <I>base</I> (the numeric
value of the decimal <FONT FACE="Arial, Helvetica">numeral</FONT> preceding
the first #) shall be at least two and at most sixteen. The <FONT FACE="Arial, Helvetica">extended_digit</FONT>s
A through F represent the digits ten through fifteen, respectively. The
value of each <FONT FACE="Arial, Helvetica">extended_digit</FONT> of
a <FONT FACE="Arial, Helvetica">based_literal</FONT> shall be less than
the base. </DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="Normal"> The conventional meaning of based notation is
assumed. An <FONT FACE="Arial, Helvetica">exponent</FONT> indicates the
power of the base by which the value of the <FONT FACE="Arial, Helvetica">based_literal</FONT>
without the <FONT FACE="Arial, Helvetica">exponent</FONT> is to be multiplied
to obtain the value of the <FONT FACE="Arial, Helvetica">based_literal</FONT>
with the <FONT FACE="Arial, Helvetica">exponent</FONT>. The <FONT FACE="Arial, Helvetica">base</FONT>
and the <FONT FACE="Arial, Helvetica">exponent</FONT>, if any, are in
decimal notation.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<DIV Class="Normal"> The <FONT FACE="Arial, Helvetica">extended_digit</FONT>s
A through F can be written either in lower case or in upper case, with
the same meaning. </DIV>
<H4 ALIGN=CENTER>Examples</H4>
<DIV Class="Paranum"><FONT SIZE=-2>9</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> <I>Examples of based
literals:</I> </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>10</FONT></DIV>
<DIV Class="SyntaxIndented">2#1111_1111# 16#FF# 016#0ff# --<I> integer literals of value 255</I><BR>
16#E#E1 2#1110_0000# --<I> integer literals of value 224</I><BR>
16#F.FF#E+2 2#1.1111_1111_1110#E11 --<I> real literals of value 4095.0</I></DIV>
<H4 ALIGN=CENTER>Wording Changes from Ada 83</H4>
<DIV Class="Paranum"><FONT SIZE=-2>10.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1>The rule about which letters are
allowed is now encoded in BNF, as suggested by Mike Woodger. This is
clearly more readable. </FONT></DIV>
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