[Mono-list] Coding advice before I raise a bug

[David Burnett]

Hi

I may have found a compiler bug, but as I'm fairly new to c# I thought I'd
run it past more experienced developers before creating a test case
and raising it formally to see if I was missing some nuisance of c#.

The code looks like something like this, its actually the top of a larger
function that has been called recursively


The variables start and end are the functions parameters an=d have the values 1 ans 2047;

private void balanceSegment(Photon[] temp, int index, int start, int end)
{
             
Console.WriteLine(String.Format("index {0}, start {1}, end {2}", index, start, end));
			
int median = 1;

while ((4 * median) <= (end - start + 1))
     median += median;

Console.WriteLine(String.Format("4 median {0}", median));

if ((3 * median) <= (end - start + 1))
{
     median += median;
     median += (start - 1);
     Console.WriteLine(String.Format("3 median {0}", median));
}
else
     median = end - median + 1;

This prints...
index 4, start 1, end 2047
4 median 512
3 median 512

It looks like the  median += median for the if statement gets ignored.
If I change that for median *= 2 it prints the correct values...

private void balanceSegment(Photon[] temp, int index, int start, int end)
{
             
Console.WriteLine(String.Format("index {0}, start {1}, end {2}", index, start, end));
	int median = 1;

while ((4 * median) <= (end - start + 1))
     median += median;

Console.WriteLine(String.Format("4 median {0}", median));

if ((3 * median) <= (end - start + 1))
{
     median *= 2;
     median += (start - 1);
     Console.WriteLine(String.Format("3 median {0}", median));
}
else
     median = end - median + 1;

index 4, start 1, end 2047
4 median 512
3 median 1024

Oh, just for completeness, if I change the line median += (start - 1) to median += (start - 2) I get

index 4, start 1, end 2047
4 median 512
3 median 511
  
which means it is just ignoring the median += median line.



So, have I missed something obvious or is this a compiler bug ?

Dave