Maxsize of array

Question

I keep getting segfalut while trying to create a array, which size is 10000000.

unsigned char anal1[10000000];

do I have to malloc for such huge variables?

Too bad. Trying to take 10 MB off the stack is just a horrible idea. Get used to Heap memory. I also recommend against calling your variables anal (unless you work for a proctologist). — abelenky
– abelenky, Commented Feb 11, 2014 at 17:06

barak manos · Accepted Answer · 2014-02-11 19:14:18Z

1

Option #1 - a local variable - the stack must be large enough to accommodate it:

void func(...)
{
    unsigned char anal1[10000000];
    ...
}

Option #2 - a static local variable - the data-section must be large enough to accommodate it:

void func(...)
{
    static unsigned char anal1[10000000];
    ...
}

Option #3 - a global variable - the data-section must be large enough to accommodate it:

unsigned char anal1[10000000];

Option #4 - a static global variable - the data-section must be large enough to accommodate it:

static unsigned char anal1[10000000];

Option #5 - if you allocate it during run-time, then the heap must be large enough to accommodate it:

unsigned char* anal1 = malloc(10000000);

Whichever option you choose, you will probably need to assert the corresponding requirement within your project settings (not sure what IDE you're using, so cannot tell you exactly how to configure that).

edited Feb 11, 2014 at 19:14

answered Feb 11, 2014 at 18:44

barak manos

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2 Comments

herohuyongtao Over a year ago

What's data-section in Option #2?

barak manos Over a year ago

global variables or local-static variables (a static variable inside a function, which I have not mentioned in the answer above)... now added (and moved options 2-3 to 3-4)

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