help on generic space

  • Thread starter Thread starter GS
  • Start date Start date
G

GS

I only dabble in C# once in a long while and am I lost. I got problem with
the following code
How should I reconcile
Color c2 = colors.Find(c1)
so I don't get
Error 1 The best overloaded method match for
'System.Collections.Generic.List<System.Drawing.Color>.Find(System.Predicate
<System.Drawing.Color>)' has some invalid arguments

===================
List<Color> colors = new List<Color>(256);
Color c1, c2;
int i, j, nc = 0, ih = bmp.Height, iw = bmp.Width;
const int IMax = 32;
for (i = 0; i < Math.Min(iw, IMax); i++)
{
//find number of colors
for (j = 0; j < Math.Min(ih,IMax); j++)
{
c1 = bmp.GetPixel(i, j);
if (i == 0 & j == 0)
{
colors.Add(c1);
}
else
{
c2 = colors.Find(c1);
if (c2 == null)
{
colors.Add(c1);
if (nc > 256)
{
MessageBox.Show("Warning - input image has
more than 256 colors and maybe rejected by Visual Studio as application
icon");
return false;
}
else nc++;
}
}
}
}
return true;
 
GS said:
I only dabble in C# once in a long while and am I lost. I got problem with
the following code
How should I reconcile
Color c2 = colors.Find(c1)
so I don't get
Error 1 The best overloaded method match for
'System.Collections.Generic.List<System.Drawing.Color>.Find(System.Predicate
<System.Drawing.Color>)' has some invalid arguments
Click to expand...

The error message itself tells you what the argument to "Find" should
be: it is expecting a Predicate<Color>, which means "a delegate to a
function that takes a Color and returns a Boolean". You can provide such a
delegate by means of a Lambda:

Color c2 = colors.Find(c=>c==c1);
 
Alberto said:
The error message itself tells you what the argument to "Find"
should be: it is expecting a Predicate<Color>, which means "a
delegate to a function that takes a Color and returns a Boolean". You
can provide such a delegate by means of a Lambda:

Color c2 = colors.Find(c=>c==c1);
Click to expand...

Or you could just use the right method. IndexOf is what most people want
when Find isn't working, for this particular case Contains would solve the
problem better. But using a better container, like a Set, would be even
better.
 
thx. I took up your suggestion and replace c2 with into int c1Idx and then
compare to less than 1. worked like a charm..

thank you again.


I must be too tired not able to think clearly.

I am somewhat better after some extra sleep although still not quite enough
quality sleep
 
But using a better container, like a Set, would be even better.
Click to expand...

What is this "Set" of which you speak? The only thing I found in MSDN was a
C++ STL thing.
 
e.g. http://www.codeplex.com/PowerCollections

I thought .NET had added a set class.... apparently it's still in beta:
http://msdn.microsoft.com/en-us/library/bb397727(VS.100).aspx
Click to expand...

No, the docs are still in beta. HashSet<T> has been in there since 3.5.

I actually posted a detailed reply to the OP when his question first
appeared, including describing HashSet<T> as a possible solution (with
code example). But, given recent problems with my posts being blocked by
Microsoft's servers, it's possible no one else saw the post:

http://groups.google.com/group/micr....csharp/browse_thread/thread/958a199d179b08d9

Pete
 
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