哪里是`％p`用printf的有用吗？ [英] Where is `%p` useful with printf?

问题描述

毕竟，这两个语句做同样的事情...

After all, both these statements do the same thing...

int a = 10;
int *b = &a;
printf("%p\n",b);
printf("%08X\n",b);

例如（使用不同的地址）：

For example (with different addresses):

0012FEE0
0012FEE0

这是小事与％X 所需的格式化指针，所以有一些很好的使用％的P 选项？

It is trivial to format the pointer as desired with %x, so is there some good use of the %p option?

推荐答案

他们不这样做同样的事情。后者 的printf 声明除$ p $点 b 为 unsigned int类型，这是错误的，因为 b 是一个指针。

They do not do the same thing. The latter printf statement interprets b as an unsigned int, which is wrong, as b is a pointer.

指针和无符号整型是不总是相同的尺寸，所以这些不能互换。当他们是不一样的尺寸（一个越来越普遍的情况下，64位CPU和操作系统变得越来越普遍），％X 只会地址的打印一半。在Mac上（也可能是其他一些系统），即将的破坏地址;输出将是错误的。

Pointers and unsigned ints are not always the same size, so these are not interchangeable. When they aren't the same size (an increasingly common case, as 64-bit CPUs and operating systems become more common), %x will only print half of the address. On a Mac (and probably some other systems), that will ruin the address; the output will be wrong.

总是使用％P 为指针。

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