From 4d10e6c5a5384fb0a9c99d9775982990a2d58ffa Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Tue, 15 Sep 2015 15:58:07 +0200
Subject: [PATCH] Binary literal exercise
---
Doc/Sd1/languageFundamentals.xml | 100 ++++++++++++++++++++++++++-----
1 file changed, 84 insertions(+), 16 deletions(-)
diff --git a/Doc/Sd1/languageFundamentals.xml b/Doc/Sd1/languageFundamentals.xml
index c582ca9a5..dcabf9c37 100644
--- a/Doc/Sd1/languageFundamentals.xml
+++ b/Doc/Sd1/languageFundamentals.xml
@@ -301,24 +301,91 @@
<section xml:id="sw1IntegerLiterals">
<title>Integer value literals</title>
- <section xml:id="sd1BinaryLiteral">
+ <section xml:id="sd1BinaryIntLiteral">
<title>Binary literals</title>
- <para>TODO:</para>
+ <qandaset defaultlabel="qanda" xml:id="sd1QandaBinaryIntLiteral">
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <orderedlist>
+ <listitem>
+ <para>Using the decimal system to represent integer values
+ we tend to ignore other important numbering systems. Write
+ an application which prints the decimal value of
+ <inlineequation>
+ <m:math display="inline">
+ <m:msub>
+ <m:mi>1110100100</m:mi>
+
+ <m:mi>2</m:mi>
+ </m:msub>
+ </m:math>
+ </inlineequation> by writing the former as a binary int
+ literal. Verify the printed value by an independent
+ calculation.</para>
+ </listitem>
+
+ <listitem>
+ <para>Then construct a second binary literal representing a
+ negative value of your choice.</para>
+ </listitem>
+ </orderedlist>
+ </question>
+
+ <answer>
+ <orderedlist>
+ <listitem>
+ <programlisting language="java"> public static void main(String[] args) {
+
+ System.out.println(0B1110100100);
+ System.out.println( 512 +
+ 256 +
+ 128 +
+ 32 +
+ 4);
+ }</programlisting>
+
+ <para>This yields:</para>
+
+ <programlisting language="none">932
+932</programlisting>
+ </listitem>
+
+ <listitem>
+ <para>A negative value in <link
+ xlink:href="http://en.wikipedia.org/wiki/Two's_complement#firstHeading">Two's
+ complement</link> representation starts with a
+ <quote>1</quote> at its highest bit. Binary literals in
+ <xref linkend="glo_Java"/> represent <code>int</code>
+ values. An <code>int</code> in <xref linkend="glo_Java"/>
+ uses 4 bytes and thus occupies 4 x 8=32 bits. Therefore
+ choosing a negative value is a simple task: Start
+ with<quote>1</quote>at the leading bit and let it follow by
+ 32 - 1 = 31 random bit values:</para>
+
+ <programlisting language="java"> public static void main(String[] args) {
+ System.out.println(0B10000000_00111001_01101001_01110100);
+ }</programlisting>
+ </listitem>
+ </orderedlist>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
</section>
<section xml:id="sw1SectHexadecimalLiterals">
<title>Hexadecimal literals</title>
- <para>Using the decimal system to represent integer values we tend to
- ignore other important numbering systems. As you may know the <xref
- linkend="glo_RGB"/> color model uses triplets of numbers to define color
- value components representing intensities of three base colors
- <foreignphrase><emphasis role="bold">R</emphasis>ed</foreignphrase>,
- <foreignphrase><emphasis role="bold">G</emphasis>reen</foreignphrase>
- and <foreignphrase><emphasis
- role="bold">B</emphasis>lue</foreignphrase>. The component values range
- from 0 to 255, the latter defining maximum intensity.</para>
+ <para>As you may know the <xref linkend="glo_RGB"/> color model uses
+ triplets of numbers to define color value components representing
+ intensities of three base colors <foreignphrase><emphasis
+ role="bold">R</emphasis>ed</foreignphrase>, <foreignphrase><emphasis
+ role="bold">G</emphasis>reen</foreignphrase> and
+ <foreignphrase><emphasis role="bold">B</emphasis>lue</foreignphrase>.
+ The component values range from 0 to 255, the latter defining maximum
+ intensity.</para>
<para>The color <quote>red</quote> for example is being represented by
(255, 0, 0). So the red component has maximum intensity, blue and green
@@ -345,11 +412,11 @@
<qandadiv>
<qandaentry>
<question>
- <para>Calculate the decimal representation of the hexadecimal
- value <inlineequation>
+ <para>Write a program printing the decimal value of the
+ hexadecimal representation <inlineequation>
<m:math display="inline">
<m:msub>
- <m:mi>CO</m:mi>
+ <m:mi>C0</m:mi>
<m:mi>16</m:mi>
</m:msub>
@@ -360,7 +427,7 @@
value <inlineequation>
<m:math display="inline">
<m:msub>
- <m:mi>CO</m:mi>
+ <m:mi>C0</m:mi>
<m:mi>16</m:mi>
</m:msub>
@@ -408,7 +475,8 @@
is <emphasis role="bold">always</emphasis> large enough to hold
color intensity values ranging from 0 to 255. Give an answer
being based on the <link
- xlink:href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html#jls-4.2.1">specification</link>.</para>
+ xlink:href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html#jls-4.2.1">specification</link>
+ and not just by try-and-error.</para>
<para>The programmer tries to adopt the <link
linkend="sw1QandaMaxMinInt">related int example</link>
--
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