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c++gdbfloating-pointnan

Stopping the debugger when a NaN floating point number is produced

I have an C++ program. Somewhere in the program (hard to reproduce, but reproduceable) a caclculation results in a float beeing set to a NaN. Since a floating point operation involving a NaN results in a NaN, this spreads fast.

Is there any way I can setup the compiler (gcc 4.4) or the debuger (gdb) to stop when a floating point operation results in a NaN? That would be extremely useful.

Thanks! Nathan

PS: It might matter: I am working under ubuntu linux 10.10.

Solution

  • You could enable floating point exceptions - see glibc Control Functions - then you'll get a SIGFPE when your NaN value is produced