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Subject:
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Beginning Visual C# Exercises - Chapter 11 Answers
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Posted By:
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seblake
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Post Date:
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9/24/2004 4:15:55 PM
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1. ... Add to the library with the Person class
public class People : DictionaryBase
{
public void AddPerson(Person newPerson)
{
Dictionary.Add(newPerson.Name, newPerson);
}
public void RemovePerson(string keyName)
{
Dictionary.Remove(keyName);
}
public People()
{
}
public Person this[string keyName]
{
get
{
return (Person)Dictionary[keyName];
}
set
{
Dictionary[keyName] = (Person)value;
}
}
}
2. ... Add to the Person class
public static bool operator >(Person person1, Person person2)
{
return person1.Age > person2.Age;
}
public static bool operator <(Person person1, Person person2)
{
return person1.Age < person2.Age;
}
public static bool operator >=(Person person1, Person person2)
{
return person1.Age >= person2.Age;
}
public static bool operator <=(Person person1, Person person2)
{
return person1.Age <= person2.Age;
}
3. ... Add to the People class
public Person[] GetOldest()
{
// default field to true for first comparison
bool isOld = true;
// Create an empty collection
ArrayList crowd = new ArrayList();
// Scan though the dictionary
foreach (DictionaryEntry theSource in this)
{
if (crowd.Count > 0)
// Test if current person's age is at least equal to collection value
isOld = ((Person)theSource.Value >= (Person)crowd[0]);
if (isOld)
{
// Now test if this current age is older than current collection
if (crowd.Count > 0 && (Person)theSource.Value > (Person)crowd[0])
{
crowd.Clear();
}
// Add this person to collection
crowd.Add((Person)theSource.Value);
}
}
Person[] result = new Person[crowd.Count];
crowd.CopyTo(result, 0);
return result;
}
4. ... Modify the People class declaration
public class People : DictionaryBase, ICloneable
... Add this method to People class
public object Clone()
{
Person twin;
People deepCopy = new People();
foreach (DictionaryEntry guy in this)
{
twin = (Person)((Person)guy.Value).Clone();
deepCopy.AddPerson(twin);
}
return deepCopy;
}
... Modify the Person class declaration
public class Person : ICloneable
... Add this method to the Person class
public object Clone()
{
// Only need a shallow copy of this class
return MemberwiseClone();
}
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