malloc(2048) failied.

[namcs]

Hi everyone,
I am trying to debug a very simple code:

double* anArray= (double*) malloc(16*16*sizeof(double));

The above statement seems to be perfectly fine to me, however, what I got was a NULL anArray.
Does any one have this problem before? I have tried several ways, which are essentially the same, but still cannot get it right:

void* anArray= malloc(2048);
or void* anArray= malloc(16*16*sizeof(double));
or double* anArray= (double)malloc(2048));

:-/

But if I use another size (could be smaller or larger e.g. malloc(1*sizeof(double))), it works.

[Athar]

See http://www.cplusplus.com/reference/clibrary/cstdlib/malloc/

[namcs]

Thanks Athat, but that doesn't help. I have been using malloc for ages, but this is the first time I get this error.

[kbw]

Perhaps you've run out of memory. Have you been freeing memory when you're done with it?

[writetonsharma]

@kbw, He said if he allocates memory smaller or larger than that size, it successful. Only this size is giving error.

Could you post your code. May be something we can find.

[namcs]

Hi kbw and writetonsharma. Yes, it only happened when I try this size (maybe some other sizes too, but I tried 1 byte and 9999 bytes, it worked in both cases).

I fixed the bug. It is due to some memory corruption in another module (very unrelated to this one). The code itself is ok. I found it's very weird how 1 part of the program and affects others in a very random manner.

Thank you all.

[kbw]

That good.

The modules aren't unrelated, they're using the same heap. If you corrupt it, it's state becomes invalid and the results of using it are non-deterministic.

[namcs]

Hi kbw, that's true. Thanks for the note =)

[zb0S216C]

Firstly, if the OS runs out of memory, it will automatically start page filing. Secondly, on line 3, you cast anArray back to a double, not a double*.