This is the first time I've seen this:
(from gdb)
what should I think about? It's a "only happens sometimes" problem.Code:Program received signal SIGSEGV, Segmentation fault. [Switching to Thread -1208293696 (LWP 3149)] 0x479850ac in malloc_consolidate () from /lib/libc.so.6
C programming resources:
GNU C Function and Macro Index -- glibc reference manual
The C Book -- nice online learner guide
Current ISO draft standard
CCAN -- new CPAN like open source library repository
3 (different) GNU debugger tutorials: #1 -- #2 -- #3
cpwiki -- our wiki on sourceforge
Well, it's just some function called within 'malloc'. My guess would be that you're program is thrashing an internal data structure, causing a seg fault when 'malloc_consolidate' is executed. Worse kind of bug...
Code:#include <cmath> #include <complex> bool euler_flip(bool value) { return std::pow ( std::complex<float>(std::exp(1.0)), std::complex<float>(0, 1) * std::complex<float>(std::atan(1.0) *(1 << (value + 2))) ).real() < 0; }
Use valgrind perhaps?
Or
gcc prog.c -lefence
and get a segfault as soon as you trash memory, and not sometime later when malloc finds out.
Run the program in the debugger, then just back-track up the stack to your line of code writing where it shouldn't.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
