如果我们开始在一些地址，我们如何确定变量占据整个程序的地址吗？ [英] If we start at some address, how can we determine the addresses that variables occupy throughout a program?

问题描述

假设内存位置地址100开始，考虑：

Assuming that the memory locations starts at address 100, consider:

int a;
struct{
    char b;
    struct{
        short *c[20];
        char d;
    }e;
}f;
double g;
char *h;

我知道 A 需要解决100-103，但我无法确定当你有一个结构会发生什么。我知道的起始地址的结构是基于最大字段对齐，和整体结构的尺寸是最大的领域的倍数，但我无法区分两者时，两个结构是如上嵌套。此外，如果我们有一个指针或数字在数组作为短* C [20] 我们如何确定通过该声明采取的内存？如果有人能在每行，我将不胜AP preciate它解释地址布局。越是这样，我就AP preciate为什么内存是这样分配的解释。

I know a takes address 100-103, but I'm having trouble determining what happens when you have a structure. I know the start address for a structure is aligned based on the largest field, and the size of the overall structure is a multiple of the largest field, but I'm having trouble distinguishing between the two when the two structures are nested as above. Also, if we have a pointer, or an array of numbers as in short *c[20] how do we determine the memory taken by this declaration? If someone can explain the address layout at each line I would greatly appreciate it. More so, I would appreciate an explanation of why the memory is assigned in this way.

感谢您的时间。

推荐答案

有没有真正的规则。它是由编译器。关于你保证全部是乙地址是电子以下地址和地址 C 是 D 。并且每个的第一要素结构的地址是一样的结构的地址。另一方面，没有保证无论为任何结构以外的元素。编译器可分配 A ，˚F，先按g 和 ^ h 在它为所欲为的任何方式。

There's no real rule. It's up to the compiler. About all you're guaranteed is that the address of b is below the address of e, and the address of c is below the address of d. And that the addresses of the first elements of each struct are the same as the address of the struct. On the other hand, there are no guarantees whatever for the elements outside of any struct. The compiler may allocate a, f, g and h in any way it pleases.

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