IComparer question

[christriddle]

Hi,

I want to be able to sort a ArrayList of Points, for example, in one of
two (or more) ways depending of the nature of the Points in the
ArrayList. Basically I want two different comparers, both of which I
could use when I want. E.g. one to sort the points in order of their X
value and another for their Y value.

I have no trouble setting up a single comparer, but I don't know how do
accomplish the task above. Any help would be appreciated!!

For example, the code I would like to use:

if (MaxX(Points) < 0)
Points.Sort(); //By X value
else
Points.Sort(); //By Y value
Thanks in advance...
Chris Riddle

[Jianwei Sun]

Instead of using ArrayList.Sort(), you really should call
ArrayList.Sort(IComparer), and pass in different implementation of
IComparer.

HTH.
ch**********@googlemail.com wrote:

Hi,

I want to be able to sort a ArrayList of Points, for example, in one of
two (or more) ways depending of the nature of the Points in the
ArrayList. Basically I want two different comparers, both of which I
could use when I want. E.g. one to sort the points in order of their X
value and another for their Y value.

I have no trouble setting up a single comparer, but I don't know how do
accomplish the task above. Any help would be appreciated!!

For example, the code I would like to use:

if (MaxX(Points) < 0)
Points.Sort(); //By X value
else
Points.Sort(); //By Y value
Thanks in advance...
Chris Riddle

[Riddle]

Thanks for the quick reply.

This is what I thought originally, but how do I implment this new
Icomparer? Is it external to the class I want to compare? Sorry, having
a bit of a slow day today!

Thanks,
Chris

[Claes Bergefall]

You can implement it anywhere you'ld like. Have its constructor take an
argument specifying the sort order that you want to use. Something like
this:

public class MyComparer : IComparer
{
private bool m_sortByX;
public MyComparer(bool sortByX)
{
m_sortByX = sortByX;
}
public int Compare(object x, object y)
{
// Sort in different order depending on m_sortByX
}
}
....
if (MaxX(Points) < 0)
Points.Sort(new MyComparer(true)); //By X value
else
Points.Sort(new MyComparer(false)); //By Y value
/claes

"Riddle" <ch**********@googlemail.comwrote in message
news:11**********************@m73g2000cwd.googlegr oups.com...

Thanks for the quick reply.

This is what I thought originally, but how do I implment this new
Icomparer? Is it external to the class I want to compare? Sorry, having
a bit of a slow day today!

Thanks,
Chris

[Riddle]

A ha... Thanks very much for you help.
I understand now.

Thanks again!
Chris