请教一个空指针自增的问题

bxb_koala

#include <stdio.h> int main() {       int i = 5;       void *p = &i;       printf("%pn", p);       ++p;       printf("%pn", p); }

以上代码void *p自增后为什么相差1？如果是int *p自增后相差sizeof(int)我能理解，但是这种情况怎么解释呢？

[ 本帖最后由 bxb_koala 于 2009-11-10 17:54 编辑 ]

yylogo

汗,, void * 能加法`? 加几个字节`?

hard2enroll

楼主把C当高级语言了

OwnWaterloo

这是非标准的gcc的扩展。 以前有帖子讨论过。

gcc文档
5.18 Arithmetic on void- and Function-Pointers
In GNU C, addition and subtraction operations are supported on pointers to void and on
pointers to functions. This is done by treating the size of a void or of a function as 1.
A consequence of this is that sizeof is also allowed on void and on function types, and
returns 1.
The option ‘-Wpointer-arith’ requests a warning if these extensions are used.