Unable to Allocate Memory

Question

I am unable to allocate memory using the following code:

int *h_VC = (int *)malloc(sizeof(int)*SIZE); //SIZE is 19200
if(h_VC==NULL)
{
 printf("Memory Not avaialble");
}

My code uses the above block in a while loop and is run several times. I have 8GB memory. I am monitoring the free memory at the same time when running the code.
The memory allocation is failing although i have arround 3GB of free memory left.
What could be the problem?

Just a note: don't cast the returned pointer of `malloc`. Theres no need to and it is possibly dangerous. — Constantinius, Dec 13 '11 at 13:03
Don't know if this is the case, but it might help: http://stackoverflow.com/questions/605845/do-i-cast-the-result-of-malloc — supertopi, Dec 13 '11 at 13:04
If it's a 32-bit program running in a 64-bit OS, you can still have plenty of free memory in the OS, but exhausted address space in the program due to memory fragmentation or leaks or just too many too big allocations. Which one it is it's hard to tell without any additional information about the program and OS. — Alexey Frunze, Dec 13 '11 at 13:31
@arncore: First, you don't have to cast a `void*` to a specific pointer type. This happens automatically and does not invoke any compiler warnings as it is mandated by the standard. It might be dangerous because you might link to another function with the name `malloc` but another return type and would not even notice, since you are explicitly casting. This would also not invoke any warnings since the compiler would assume you know what you are doing. Avoid explicit casts, unless necessary is a good rule of thumb. — Constantinius, Dec 13 '11 at 14:02
@Alex: agreed. If it's 32 bit, and really 5GB allocated, then the OS deals with a "-1GB" linear address space situation, and must be swapping like crazy to handle. — gnometorule, Dec 13 '11 at 14:13

score 5 · Answer 1 · answered Dec 13 '11 at 13:03

5

Anything could be the problem. Replace the printf with

perror("");

to get a hint.

answered Dec 13 '11 at 13:03

Fred Foo

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Except beer... Beer is never the problem... +1 – Luchian Grigore Dec 13 '11 at 13:09
4

*Beer is the cause and the solution to all problems in life.* - Homer J. Simpson – Constantinius Dec 13 '11 at 14:03

score 0 · Accepted Answer · answered Dec 14 '11 at 10:09

0

I am using Visual Studio as a compiler. Compiling the program as x64 solved the issue.
thanks to Alex's comment.

answered Dec 14 '11 at 10:09

scatman

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Unable to Allocate Memory

2 Answers2