浮动价值突然变得巨大

Question

I would rather not dump code, but explain my problem. After hours of debugging I managed to understand that at some point in my code, a float value that is not explicitly modified turns HUGE (more than 1e15). I do use a lot of memory in my program (a string array containing 800+ words), other than that though, I have no idea what could cause this.

If anyone has any ideas regarding this, please share. Otherwise, I'll post a pastebin of the code soon.

EDIT: Here is the code: http://pastebin.com/vgiZweNq . The problem rests in the next_generation() function, where the sumfit variable goes nuts at random times in the loop.

Also, I've compiled this on linux using -fno-stack-limit and -fstack-check , to avoid stack overflows.

EDIT 2: I've changed the program to use a dynamically allocated linked list, to further avoid stack overflows. Still, sumfit gets changed to Floatzilla at random points, usually pretty early on.

Cheers!

Answer 1

Since the variable is obviously being modified from an unexpected point, you might want to check some possibilities:

• Is it being modified from a different thread or from an interrupt / event handler? If so, is the access properly synchronized to prevent a data race?
• Are you doing pointer arithmetic that might be buggy and cause access outside the intended buffer?
• Are you casting pointers between types of different sizes?
• Especially if you are working on an embedded device: Maybe the memory is full and your stack is overlapping the heap, or the global variables.

More information about the platform this happens on would be helpful.

Answer 2

You're using strcpy on the chrom array, but i don't see where they ever get null terminated.

Maybe I'm just missing it, though.

Answer 3

You've got a huge string array. I reckon you're probably going off the end of it. Keep track of the size of data going into that array.