[ROOT] Strange seg faults

From: Gregory Novak (Gregory.Novak@cern.ch)
Date: Fri Mar 02 2001 - 02:12:38 MET 

I'm using Root 2.25.03 and I'm getting segmentation faults I don't
understand.  This has something to do with array allocation and
function arguments.  I'm loading a bunch of c++ code via .L, containing
the following two functions:

void profMedian2(Float_t x[], Float_t y[], const Int_t nBins) {
  for (Int_t i=0; i<nBins; i++) {
    sliceMedian2(x,y,nBins);
  }
}

Float_t sliceMedian2(Float_t x[], Float_t y[], const Int_t n) {
  Float_t sortedX[n];
  return 0;
}

Then I have the following in a macro.   
 {
  Float_t x[500]; 
  Float_t y[500]; 
  profMedian2(x, y, 500);
}

When I run the macro, Root gives me a segmentation fault.  There are a few
things that are confusing: The seg fault comes when root tries to call
sliceMedian2, but I can run it directly without trouble.  If I change the
arguments of sliceMedian2 or profMedian2, the seg fault goes away.  Also,
if I take out the for loop around the call to sliceMedian2, the seg fault
goes away.  This is in spite of the fact that the seg fault comes on the
first pass through the loop.

So, is there any solution to this?

Thanks!
Greg

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