Questions on usages of sizeof
- by Appu
Question 1
I have a struct like,
struct foo
{
int a;
char c;
};
When I say sizeof(foo), i am getting 8 on my machine. As per my understanding, 4 bytes for int, 1 byte for char and 3 bytes for padding. Is that correct? Given a struct like the above, how will I find out how many bytes will be added as padding?
Question 2
I am aware that sizeof can be used to calculate the size of an array. Mostly I have seen the usage like (foos is an array of foo)
sizeof(foos)/sizeof(*foos)
But I found that the following will also give same result.
sizeof(foos) / sizeof(foo)
Is there any difference in these two? Which one is preffered?
Question 3
Consider the following statement.
foo foos[] = {10,20,30};
When I do sizeof(foos) / sizeof(*foos), it gives 2. But the array has 3 elements. If I change the statement to
foo foos[] = {{10},{20},{30}};
it gives correct result 3. Why is this happening?
Any thoughts..
