指针/地址差异 [英] Pointer/Address difference

问题描述

为什么两个地址的区别是错误的?http://codepad.org/NGDqFWjJ

Why is the difference between the two addresses wrong? http://codepad.org/NGDqFWjJ

#include<stdio.h>
int main()
{
   int i = 10, j = 20;
   int *p = &i;
   int *q = &j;
   int c = p - q;
   printf("%d
", p);
   printf("%d
", q);
   printf("%d", c);
   return 0;
}

输出:

-1083846364
-1083846368
1

推荐答案

首先，当对不相关的指针执行时，没有定义指针算法.

First, pointer arithmetic isn't defined when performed on unrelated pointers.

其次，这是有道理的.减去指针时，您会得到这些地址之间的元素数，而不是字节数.

Second, it makes sense. When subtracting pointers you get the number of elements between those addresses, not the number of bytes.

如果你想试试

char *p1 = &i, *p2 = &j;

你会得到不同的结果.

作为旁注，打印指针时使用 %p.

As a side note, use %p when printing pointers.

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