c - int *p 应该改为 long int *p 吗？

Question

我正在通过阅读 K&R 和做练习来学习 c。我现在在讨论指针的第 5 章。我不明白为什么声明:

int *p;

不是:

long int *p;

因为 *p 包含地址并且不能保证 int 类型的变量足够大以容纳大地址。或者有吗？

Answer 1

int 是指针指向的对象的类型，而不是指针本身的大小。指针的大小与其指向的对象无关

例如:

int *p;

double *d;

指针 p 和 d “通常”具有相同的大小，但它们指向的数据不具有相同的大小。

编辑:正如评论中指出的那样，指针实际上并不“需要”具有相同的大小。

正如约翰所解释的:

For instance, a char * on a word-addressed system may actually be larger than an int *, since it needs to specify an offset into the word. The only guarantees are that void * and char * have the same alignment and representation, that pointers to compatible types have the same alignment and representation, that pointers to struct types have the same alignment and representation, and pointers to union types all have the same alignment and representation