From dc18a84139478fc828ba4dd844bf3a93c4647c9c Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Mon, 16 Mar 2015 18:49:34 +0100
Subject: [PATCH] variable assignment related exercises
---
Doc/Sd1/languageFundamentals.xml | 401 ++++++++++++++++++++++++++++++-
Doc/Sd1/preliminaries.xml | 5 +-
Doc/Sd1/steinbruch.xml | 63 +++++
Doc/lectures.xml | 4 +-
4 files changed, 465 insertions(+), 8 deletions(-)
diff --git a/Doc/Sd1/languageFundamentals.xml b/Doc/Sd1/languageFundamentals.xml
index fd2e61fc3..742aae520 100644
--- a/Doc/Sd1/languageFundamentals.xml
+++ b/Doc/Sd1/languageFundamentals.xml
@@ -9,6 +9,294 @@
xmlns:db="http://docbook.org/ns/docbook">
<title>Language Fundamentals</title>
+ <section xml:id="sw1LegalVariableName">
+ <title>Legal variable names</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaLegalVarNames">
+ <title>Legal variable names</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Which of the following names are legal variable names?
+ Complete the following table and explain your decision with
+ respect to the <quote
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc4_html_3">variables</quote>
+ section.</para>
+
+ <informaltable border="1">
+ <colgroup width="19%"/>
+
+ <colgroup width="10%"/>
+
+ <colgroup width="71%"/>
+
+ <tr>
+ <th>Identifier</th>
+
+ <th>is legal? (yes / no)</th>
+
+ <th>Explanation / remark</th>
+ </tr>
+
+ <tr>
+ <td><code>for</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>sum_of_data</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>sumOfData</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>first-name</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>ABC</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>42isThesolution</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>println</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>B4</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>AnnualSalary</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>"hello"</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>_average </code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>ανδÏος</code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>$sum </code></td>
+
+ <td/>
+
+ <td/>
+ </tr>
+ </informaltable>
+
+ <tip>
+ <para>You may want to prepare a simple <xref
+ linkend="glo_Java"/> program and just test the above
+ names.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>We may write a small <xref linkend="glo_Java"/>
+ program:</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+ int 42isThesolution = 6; // <emphasis role="bold">Syntax error on token "42", delete this token</emphasis>
+}</programlisting>
+
+ <para>Unfortunately the error explanation is not too helpful with
+ respect to <xref linkend="glo_Java"/> beginners. It does not
+ immediately point towards an illegal identifier problem. One
+ indication of a sound compiler is its ability to provide
+ meaningful, self explanatory error messages.</para>
+
+ <informaltable border="1">
+ <colgroup width="19%"/>
+
+ <colgroup width="10%"/>
+
+ <colgroup width="71%"/>
+
+ <tr>
+ <th>Identifier</th>
+
+ <th>is legal? (yes / no)</th>
+
+ <th>Explanation / remark</th>
+ </tr>
+
+ <tr>
+ <td><code>for</code></td>
+
+ <td>no</td>
+
+ <td><code>for</code> is a Java keyword.</td>
+ </tr>
+
+ <tr>
+ <td><code>sum_of_data</code></td>
+
+ <td>yes</td>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>sumOfData</code></td>
+
+ <td>yes</td>
+
+ <td/>
+ </tr>
+
+ <tr>
+ <td><code>first-name</code></td>
+
+ <td>no</td>
+
+ <td>Operators like <quote>-</quote> must not appear in
+ variable names.</td>
+ </tr>
+
+ <tr>
+ <td><code>ABC</code></td>
+
+ <td>yes</td>
+
+ <td>Best practices: Discouraged variable name, non-constant
+ variables should start with lowercase letters.</td>
+ </tr>
+
+ <tr>
+ <td><code>42isThesolution</code></td>
+
+ <td>no</td>
+
+ <td>Identifiers must not start with a number.</td>
+ </tr>
+
+ <tr>
+ <td><code>println</code></td>
+
+ <td>yes</td>
+
+ <td><code>println</code> is part of
+ <code>System.out.println(...)</code> but is no <xref
+ linkend="glo_Java"/> keyword.</td>
+ </tr>
+
+ <tr>
+ <td><code>B4</code></td>
+
+ <td>yes</td>
+
+ <td>Best practices: Discouraged variable name, non-constant
+ variables should start with lowercase letters.</td>
+ </tr>
+
+ <tr>
+ <td><code>AnnualSalary</code></td>
+
+ <td>yes</td>
+
+ <td>Best practices: Discouraged variable name, non-constant
+ variables should start with lowercase letters.</td>
+ </tr>
+
+ <tr>
+ <td><code>"hello"</code></td>
+
+ <td>no</td>
+
+ <td>String delimiters must not be part of an identifier.</td>
+ </tr>
+
+ <tr>
+ <td><code>_average </code></td>
+
+ <td>yes</td>
+
+ <td>Best practices: Should be reserved for system code.</td>
+ </tr>
+
+ <tr>
+ <td><code>ανδÏος</code></td>
+
+ <td>yes</td>
+
+ <td>Perfectly legal Greek <orgname>Unicode</orgname>
+ characters.</td>
+ </tr>
+
+ <tr>
+ <td><code>$sum </code></td>
+
+ <td>yes</td>
+
+ <td>Best practices: Should be reserved for system code.</td>
+ </tr>
+ </informaltable>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+
<section xml:id="sw1IntegerLiterals">
<title>Integer value literals</title>
@@ -353,7 +641,7 @@ System.out.println("Maximum short value:" + maximum);
<para>Since a short ranges from -32768 to 32767 we may as well
use a unary minus sign instead:</para>
- <programlisting>short minumum = -0B10000000_00000000;</programlisting>
+ <programlisting language="java">short minumum = -0B10000000_00000000;</programlisting>
</answer>
</qandaentry>
</qandadiv>
@@ -463,7 +751,7 @@ System.out.println("Maximum short value:" + maximum);
<title>Strange things happen</title>
<qandaset defaultlabel="qanda" xml:id="sw1QandaByteOverflow">
- <title>Calculating the area of a square</title>
+ <title>Byte integer arithmetics</title>
<qandadiv>
<qandaentry>
@@ -527,8 +815,113 @@ System.out.println("New value=" + a);</programlisting>
<para>On machine level the above calculation is just an ordinary
addition.</para>
- <para>Conclusion: Watch out when doing (integer) arithmetic!
- </para>
+ <para>Conclusion: Watch out when doing (integer)
+ arithmetic!</para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+
+ <section xml:id="sw1SectAssignArithmetics">
+ <title>Assignments and simple arithmetics</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaGuessingResults">
+ <title>Guessing results</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Consider the following code segment:</para>
+
+ <programlisting language="java"> int a = 3;
+ a++; //Incrementing a by 1 --> a==4
+
+ int b = a; // TODO
+
+ b--; // TODO
+ --b; // TODO
+
+ int c = b; // TODO
+
+ b = ++a; // TODO
+ int e = a++; // TODO
+
+ a *= b; // TODO
+
+ System.out.println("a=" + a);
+ System.out.println("b=" + b);
+ System.out.println("c=" + c);
+ System.out.println("e=" + e);</programlisting>
+
+ <para>We want to guess the expected result. Copy/paste the above
+ code into a main() method body within your IDE of choice
+ (probably Eclipse). Though it is tempting to just execute this
+ code ant watch the results <emphasis role="bold">please refrain
+ from doing so!</emphasis></para>
+
+ <para>Instead start a <quote>dry run</quote> complete the above
+ comments to predict the expected outcome:</para>
+
+ <para><computeroutput>a=...</computeroutput></para>
+
+ <para><computeroutput>b=...</computeroutput></para>
+
+ <para><computeroutput>c=...</computeroutput></para>
+
+ <para><computeroutput>e=...</computeroutput></para>
+
+ <para>After finishing your guesses execute your code and start
+ wailing about your success rate.</para>
+
+ <tip>
+ <para>Both <code>x++</code> (postfix notation) and
+ <code>++x</code> (infix notation) are expressions themselves
+ which might even be rewritten as <code>(x++)</code> and
+ <code>(++x)</code> for clarity. The difference is not about
+ operator precedence rules but simply about the values of these
+ expressions when e.g. being assigned.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>As inferred by the hint the biggest problem is about
+ understanding postfix and infix notation of the operators
+ <code>++</code> and <code>--</code>. A corresponding expression
+ evaluates to:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para><code>a = x++</code> yields a ==x </para>
+ </listitem>
+
+ <listitem>
+ <para><code>a = ++x</code> yields a ==(x + 1)</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>The rest is just obeying the <quote>due diligence</quote>
+ rule set:</para>
+
+ <programlisting language="java"> int a = 3;
+ a++; //Incrementing a by 1 --> a==4
+
+ int b = a; // Assigning value of a --> b==4
+
+ b--; // Decrementing b by 1 --> b==3
+ --b; // Decrementing b by 1 --> b==2
+
+ int c = b; // c == 2;
+
+ b = ++a; // Incrementing a by 1 -->a==5, then assigning to b --> b == 5
+ int e = a++; // Assigning a to e --> e==5, then incrementing a --> a==6
+
+ a *= b; // Multiplying a with b and assigning the result to a --> a==30
+
+ System.out.println("a=" + a);
+ System.out.println("b=" + b);
+ System.out.println("c=" + c);
+ System.out.println("e=" + e);</programlisting>
</answer>
</qandaentry>
</qandadiv>
diff --git a/Doc/Sd1/preliminaries.xml b/Doc/Sd1/preliminaries.xml
index 571c0bc35..e7320b78a 100644
--- a/Doc/Sd1/preliminaries.xml
+++ b/Doc/Sd1/preliminaries.xml
@@ -6,7 +6,7 @@
xmlns:m="http://www.w3.org/1998/Math/MathML"
xmlns:html="http://www.w3.org/1999/xhtml"
xmlns:db="http://docbook.org/ns/docbook">
- <title>Lecture 1</title>
+ <title>Preliminaries</title>
<section xml:id="sd1CommonRessources">
<title>Common software development related resources</title>
@@ -174,7 +174,8 @@
<listitem>
<para><link
xlink:href="http://wiki.eclipse.org/Eclipse/Installation">Installation</link>,
- choose <quote>Eclipse IDE for Java Developers</quote> from <link
+ choose <quote>Eclipse IDE for Java EE Developers</quote> from
+ <link
xlink:href="http://eclipse.org/downloads">http://eclipse.org/downloads</link>.</para>
</listitem>
</itemizedlist>
diff --git a/Doc/Sd1/steinbruch.xml b/Doc/Sd1/steinbruch.xml
index 90c9d3e53..f0ad7e073 100644
--- a/Doc/Sd1/steinbruch.xml
+++ b/Doc/Sd1/steinbruch.xml
@@ -131,4 +131,67 @@ public class CircleAreaCalculator {
</qandaentry>
</qandadiv>
</qandaset>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaExamBonuspoints">
+ <title>Exam bonus points</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>After completely marking an examination a lecturer decides to
+ globally add a number extra points to a specific task . There is an
+ upper limit of points for the task in question. We provide an
+ example:</para>
+
+ <para>On completely fulfilling a task 12 points will be awarded. So
+ after marking the exam participants' points range from 0 to 12
+ points.</para>
+
+ <para>Basically our lecturer wants to add three more points without
+ breaching the 12 point limit.</para>
+
+ <para>Complete the following code for variable by assigning the
+ variable <code>newResult</code>. The values of
+ <code>maximumPoints</code> and <code>pointsToAdd</code> may be
+ adjusted.</para>
+
+ <programlisting language="java"> public static void main(String[] args) {
+
+ int pointsReached = 1;
+ int maximumPoints = 12;
+ int pointsToAdd = 3;
+
+ final int newResult;
+
+ // TODO: Assignment to variable newResult
+
+ System.out.println("New Result:" + newResult);
+ }</programlisting>
+ </question>
+
+ <answer>
+ <para>The basic task is to add up the values of
+ <code>pointsReached</code> and <code>pointsToAdd</code>. When
+ exceeding the limit we just assign the limit itself:</para>
+
+ <programlisting language="java"> public static void main(String[] args) {
+
+ int pointsReached = 1;
+ int maximumPoints = 12;
+ int pointsToAdd = 3;
+
+ final int newResult;
+
+ if (maximumPoints <= pointsReached + pointsToAdd) {
+ newResult = maximumPoints;
+ } else {
+ newResult = pointsReached + pointsToAdd;
+ }
+
+ System.out.println("New Result:" + newResult);
+ }</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
</chapter>
diff --git a/Doc/lectures.xml b/Doc/lectures.xml
index c4c886c98..d0fc71fd3 100644
--- a/Doc/lectures.xml
+++ b/Doc/lectures.xml
@@ -33,8 +33,6 @@
<xi:include href="Sd1/languageFundamentals.xml" xpointer="element(/1)"/>
- <xi:include href="Sd1/steinbruch.xml" xpointer="element(/1)"/>
-
<xi:include href="Sd1/class.xml" xpointer="element(/1)"/>
<xi:include href="Sd1/loop.xml" xpointer="element(/1)"/>
@@ -48,6 +46,8 @@
<xi:include href="Sd1/streams.xml" xpointer="element(/1)"/>
<xi:include href="Sd1/collections.xml" xpointer="element(/1)"/>
+
+ <xi:include href="Sd1/steinbruch.xml" xpointer="element(/1)"/>
</part>
<part xml:id="sda1">
--
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