C多维数组是连续的，没有孔吗? [英] Are C multidimensional arrays contiguous without holes?

问题描述

我无法在C标准文档中特别找到多维数组是连续的.虽然可以从

I am unable to find in the C standard docs specifically where it says that multidimensional arrays are contiguous. While it can be inferred from the fact that array elements are contiguous, I want some perspective from the community.

The following code prints out the numbers in the order that I would expect, which is 1 - 9.

#include <stdio.h>

int main()
{
    int a[][3] = {{1,2,3},{4,5,6},{7,8,9}};
    int* p = (int*)a;
    int i;

    for (i = 0; i < sizeof(a)/sizeof(int); i++)
        printf("%d ",p[i]);

    return 0;
}

解决方案

Yes, it can be obtained by induction. (Just to add, as a suggestion, if that helps, try to think of multi-dimensional arrays as array of arrays.)

For example, consider an array like a[3][3].

• So, a[0][0], a[0][1] and a[0][2] are elements of a[0] and they will be contiguous.

• Next, a[0] and a[1] are elements of a, so it will be contiguous

an so on.

Taken together, a[0][2] and a[1][0] will be residing next to each other, thereby continuing the contiguity.

For better visual representation, see the below illustration.

The array, say int arr[4][5], has four rows, a[0],a[1], a[2] and a[3] and they are contiguous.

Now each of those rows have five columns, like a[n][0], a[n][1], a[n][2], a[n][3], a[n][4] and they are contiguous.

So, the all the elements (and elements of elements) of the array are contiguous.

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