&QUOT值;多维数组指针+ 1"不匹配 [英] The value of "multidimensional array pointer +1" doesn't match
问题描述
这里的问题是程序:
#include <stdio.h>
int main()
{
int apricot[2][3][5];
int (*r)[5]=apricot[0];
int *t=apricot[0][0];
printf("%p\n%p\n%p\n%p\n",r,r+1,t,t+1);
}
它的输出是:
# ./a.out
0xbfa44000
0xbfa44014
0xbfa44000
0xbfa44004
我觉得T的维度的值应为5,因为t是最后一个维度和事实吻合(0xbfa44004-0xbfa44000 + 1 = 5)
I think t's dimension's value should be 5 because t is the last dimension,and the fact is matched(0xbfa44004-0xbfa44000+1=5)
不过的r维的值为 0xbfa44014-0xbfa44000 + 1 = 21,我想应该是3 * 5 = 15 ,因为3和5的最后两个维度,那么,为什么不同的是21?
But the r's dimension's value is 0xbfa44014-0xbfa44000+1=21,I think it should be 3*5=15,because 3 and 5 are the last two dimensions,then why the difference is 21?
推荐答案
研究
是一个指向5 int数组。
r
is a pointer to an array of 5 ints.
假设1 int是您的系统上的4个字节(从 T
和 T + 1
),然后在踩着这个指针1( R + 1
)指5 * 4 = 20个字节的增加。这就是你在这里。
Assuming 1 int is 4 bytes on your system (from t
and t+1
), then "stepping" that pointer by 1 (r+1
) means an increase in 5*4 = 20 bytes. Which is what you get here.
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