Chapter 11 Ch10Ex05

dampyr · November 19th, 2011, 01:25 PM

namespace Ch11Ex05
{
class Person: IComparable
{
public string Name;
public int Age;

public Person(string name, int age)
{
Name = name;
Age = age;
}

public int CompareTo(object obj)
{
if (obj is Person)
{
Person otherPerson = obj as Person;
return this.Age + otherPerson.Age;
}
else
{
throw new ArgumentException(
"Object to compare to is not a Person object.");
}
}
}
}

WHAT MEANS

return this.Age - otherPerson.Age;
i replaced - with +

and results are:
people sorted with default comparer by age:
Bert 27
Jim 30
Ernie 22
Bob 25

Peoples are not sorted by age

Initials data:

ArrayList list = new ArrayList();
list.Add(new Person("Jim", 30));
list.Add(new Person("Bob", 25));
list.Add(new Person("Bert", 27));
list.Add(new Person("Ernie", 22));

ChristianNagel · November 19th, 2011, 03:37 PM

The return value of CompareTo should be 0 if both objects have the same order value, or a minus or a positive value depending if the first or the second object should go first. An easy way to compare this is by invoking the CompareTo method of the Int32 type.

Code:

public int CompareTo(object obj)
{
if (obj is Person)
{
Person otherPerson = obj as Person;
return this.Age.CompareTo(therPerson.Age);
}
else
{
throw new ArgumentException(
"Object to compare to is not a Person object.");
}
}

dampyr · November 20th, 2011, 06:35 AM

Thanks again,i have one question:I want to dive into database programming (MS SQL ) using c#,that's why i bought this book,to learn basic c#.Which book(s) would you recommend for developing database applications using c#.I have solid knowledge of SQL language/?