Re: Newbie: BGL: g++ -O2 or -O3 gives wrong numbers

From: Vladimir Prus (yg-boost-users_at_[hidden])
Date: 2003-06-17 07:45:43

michael_wangzy wrote:

> HI,
>   I start looking at the Graph library and try the quick_tour.cpp
> on my machine. Here is something wrong I found out
> 
>> gcc --vesion
> gcc (GCC) 3.3 (Gentoo Linux 1.4, PVR 3.3)
> 
>> g++ -o test -O2 quick_tour.cpp
>> ./test
> vertices(g) = A B C D E
> edges(g) = (A,B) (A,D) (C,A) (D,C) (C,E) (B,D) (D,E)
> vertex: 0
>         out-edges: (0,134545512) (0,134545536)

...

> Note: the large numbers in the out-edges , like 134545512. Expected
> numbers are 0,1,2,3,4. Seems some fields are not initilized but read.

Hmm... here with 3.3 on Debian it works ok. Do you have 'valgrind' utility
installed or easily installable on your box. If so, you might run

  valgrind test

and tell if it spots any uninitialized memory reads. If that does not help,
I'm at loss...

- Volodya