sizeof struct

I'm running the following prog :

Code:

---

#include <iostream>

using namespace std;

struct customer {
    short number;      //  1:
    int postcode;        //  2:
};

int main() {

    cout<<sizeof(customer)<<endl;

}

---

If I run it with line 1 in comments the output is 4.OK for that.
If I run it with line 2 in comments the output is 2.OK for that too.
But if i run it as it is above the outout is 8.Why is that?

Thank you in advance.

Because the compiler belives that aligning structs to 4- or 8-byte boundaries will make your program faster.

"Because the compiler belives that aligning structs to 4- or 8-byte boundaries will make your program faster."


???
That doesn't explain why sizeof (customer) will return 2 if there is only 1 short int, or 6 if there are 3 short ints (and no ints), yet if there are 3 short ints plus 1 int, it returns 12.

Does it align structs that way only when they contain ints?

Stick to one thread.