From 8db4d2e3bb8bddfff3d4e3a042676b98fdf47dab Mon Sep 17 00:00:00 2001
From: "Dr. Martin Goik" <goik@hdm-stuttgart.de>
Date: Wed, 24 Jun 2020 15:38:15 +0200
Subject: [PATCH] Leap year exercise frpm 'switch' to 'if' section
---
Doc/Sd1/statements.xml | 181 +++++++++++++++++++++--------------------
Doc/Sdi/apache.xml | 9 +-
2 files changed, 97 insertions(+), 93 deletions(-)
diff --git a/Doc/Sd1/statements.xml b/Doc/Sd1/statements.xml
index 60fd75d6f..a17bb46b2 100644
--- a/Doc/Sd1/statements.xml
+++ b/Doc/Sd1/statements.xml
@@ -1488,6 +1488,97 @@ Decimal value 11 not yet implemented</screen>
}
}</programlisting>
</figure>
+
+ <qandaset defaultlabel="qanda" xml:id="sd1QandaLeapYear">
+ <title>Leap years</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>We want to write an application telling whether a given
+ year is a leap year or not. The following dialogue may serve as
+ an example:</para>
+
+ <screen>Enter a year:>1980
+Year 1980 is a leap year</screen>
+
+ <screen>Enter a year:>1900
+Year 1900 is no leap year</screen>
+
+ <para>You may reuse the user input handling code from the
+ previous examples.</para>
+
+ <tip>
+ <para>Read about the <link
+ xlink:href="https://en.wikipedia.org/wiki/Leap_year#Algorithm">leap
+ year algorithm</link>.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>A first straightforward rule translation based solution
+ reads:</para>
+
+ <programlisting language="java">package start;
+
+import java.util.Scanner;
+
+public class LeapYear {
+
+ public static void main(String[] args) {
+
+ try (final Scanner scan = new Scanner(System.in)) {
+
+ System.out.print("Enter a year:>");
+ final int year = scan.nextInt();
+
+ if (0 == year % 400) { <emphasis role="bold"> // Every 400 years we do have a leap year.</emphasis>
+ System.out.println(
+ "Year " + year + " is a leap year");
+ } else if (0 == year % 4 && <emphasis role="bold"> // Every 4 years we do have a leap year</emphasis>
+ 0 != year % 100) { <emphasis role="bold"> // unless year is a multiple of 100.</emphasis>
+ System.out.println("Year " + year + " is a leap year");
+ } else {
+ System.out.println("Year " + year + " is no leap year");
+ }
+ }
+ }
+}</programlisting>
+
+ <para>This solution contains two identical <code
+ language="java">println("Year " + year + " is a leap
+ year")</code> statements. Developers don't favour redundancies:
+ Rearranging and combining the first and third <code
+ language="java">if</code> branch into one resolves the
+ issue:</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+ ...
+ if (0 == year % 400 || <emphasis role="bold">// Every 400 years we do have a leap year.</emphasis>
+ (0 == year % 4 && <emphasis role="bold">// Every 4 years we do have a leap year</emphasis>
+ 0 != year % 100)) { <emphasis role="bold">// unless year is a multiple of 100.</emphasis>
+ System.out.println("Year " + year + " is a leap year");
+ } else {
+ System.out.println("Year " + year + " is no leap year");
+ }
+...</programlisting>
+
+ <para>Some enthusiasts prefer compact expressions at the expense
+ of readability (<quote>Geek syndrome</quote>) sometimes referred
+ to as <quote>syntactic sugar</quote>. The following code based
+ on the <code language="java"
+ xlink:href="https://www.geeksforgeeks.org/java-ternary-operator-with-examples">...?
+ ...: ...</code> operator is fully equivalent:</para>
+
+ <programlisting language="java">...
+
+System.out.println("Year " + year +
+ (year % 400 == 0 || year % 4 == 0 && 0 != year % 100 ? " is a leap year" : " is no leap year"));
+}</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
</section>
</section>
@@ -1955,96 +2046,6 @@ Midweek</screen>
</qandaentry>
</qandadiv>
</qandaset>
-
- <qandaset defaultlabel="qanda" xml:id="sd1QandaLeapYear">
- <title>Leap years</title>
-
- <qandadiv>
- <qandaentry>
- <question>
- <para>We want to write an application telling whether a given year
- is a leap year or not. The following dialogue may serve as an
- example:</para>
-
- <screen>Enter a year:>1980
-Year 1980 is a leap year</screen>
-
- <screen>Enter a year:>1900
-Year 1900 is no leap year</screen>
-
- <para>You may reuse the user input handling code from the previous
- examples.</para>
-
- <tip>
- <para>Read about the <link
- xlink:href="https://en.wikipedia.org/wiki/Leap_year#Algorithm">leap
- year algorithm</link>.</para>
- </tip>
- </question>
-
- <answer>
- <para>A first straightforward rule translation based solution
- reads:</para>
-
- <programlisting language="java">package start;
-
-import java.util.Scanner;
-
-public class LeapYear {
-
- public static void main(String[] args) {
-
- try (final Scanner scan = new Scanner(System.in)) {
-
- System.out.print("Enter a year:>");
- final int year = scan.nextInt();
-
- if (0 == year % 400) { <emphasis role="bold"> // Every 400 years we do have a leap year.</emphasis>
- System.out.println(
- "Year " + year + " is a leap year");
- } else if (0 == year % 4 && <emphasis role="bold"> // Every 4 years we do have a leap year</emphasis>
- 0 != year % 100) { <emphasis role="bold"> // unless year is a multiple of 100.</emphasis>
- System.out.println("Year " + year + " is a leap year");
- } else {
- System.out.println("Year " + year + " is no leap year");
- }
- }
- }
-}</programlisting>
-
- <para>This solution contains two identical <code
- language="java">println("Year " + year + " is a leap year")</code>
- statements. Developers don't favour redundancies: Rearranging and
- combining the first and third <code language="java">if</code>
- branch into one resolves the issue:</para>
-
- <programlisting language="java">public static void main(String[] args) {
- ...
- if (0 == year % 400 || <emphasis role="bold">// Every 400 years we do have a leap year.</emphasis>
- (0 == year % 4 && <emphasis role="bold">// Every 4 years we do have a leap year</emphasis>
- 0 != year % 100)) { <emphasis role="bold">// unless year is a multiple of 100.</emphasis>
- System.out.println("Year " + year + " is a leap year");
- } else {
- System.out.println("Year " + year + " is no leap year");
- }
-...</programlisting>
-
- <para>Some enthusiasts prefer compact expressions at the expense
- of readability (<quote>Geek syndrome</quote>) sometimes referred
- to as <quote>syntactic sugar</quote>. The following code based on
- the <code language="java"
- xlink:href="https://www.geeksforgeeks.org/java-ternary-operator-with-examples">...?
- ...: ...</code> operator is fully equivalent:</para>
-
- <programlisting language="java">...
-
-System.out.println("Year " + year +
- (year % 400 == 0 || year % 4 == 0 && 0 != year % 100 ? " is a leap year" : " is no leap year"));
-}</programlisting>
- </answer>
- </qandaentry>
- </qandadiv>
- </qandaset>
</section>
<section xml:id="sd1_sect_loops">
diff --git a/Doc/Sdi/apache.xml b/Doc/Sdi/apache.xml
index 0620d25df..6f3ecc7af 100644
--- a/Doc/Sdi/apache.xml
+++ b/Doc/Sdi/apache.xml
@@ -1,7 +1,6 @@
<?xml version="1.0" encoding="UTF-8"?>
-<chapter version="5.1" xml:id="sdiApache"
- annotations="slide"
- xmlns="http://docbook.org/ns/docbook"
+<chapter annotations="slide" version="5.1" xml:id="sdiApache"
+ xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xila="http://www.w3.org/2001/XInclude/local-attributes"
xmlns:xi="http://www.w3.org/2001/XInclude"
@@ -323,6 +322,10 @@
</listitem>
</orderedlist>
+ <para>It fully suffices to get the <productname>firefox</productname>
+ browser working this way. <productname>Google-Chrome</productname> is
+ known for additional security restrictions.</para>
+
<para>The following docs may help you:</para>
<tip>
--
GitLab