Is there a way to keep some members of a struct unmodifiable?

Question

I have a struct :

struct ABC
{
   int size;
   int arr[15];
};

I know I cannot make 'int size' as 'const int size' so how can I keep the size member from being modified accidently/intentionally.Is there a way around in C?

Thanks.

It's a duplicate of this: http://stackoverflow.com/questions/5368028/how-to-make-struct-members-private — littleadv, Jun 06 '11 at 07:45

score 7 · Accepted Answer · answered Jun 06 '11 at 07:44

7

It can be const:

struct ABC
{
   const int size;
   int arr[15];
};

int main() {
    struct ABC a = {3, {1,2,3} };   // ok
    a.size = 42;    // error
}

answered Jun 06 '11 at 07:44

2

This will not prevent intentional modification though pointer manipulation. Just as a note for the OP. – rerun Jun 06 '11 at 07:56
@Neil-isn't this(struct var initialization) a feature of C99? – rsjethani Jun 06 '11 at 09:34
@ryan Sorry, I'm not sure what you are asking about - you've always been able to initialise structs. and C99 *is* what C is today - it's not some weird offshoot. – Jun 06 '11 at 09:42
@ryanlancer: You're probably thinking of designated initializers, which were added in C99. That isn't this. – jamesdlin Jun 06 '11 at 10:22

Is there a way to keep some members of a struct unmodifiable?

1 Answers1