以下程序功能是：计算矩阵所有周边元素的和。#include 'stdio.h'#define M 4#define N 3void main( ){int a[M][N]={{1,2,3},{4,5,6},{7,8,9},{10,11,12}};int sum= ① ,i,j;for(i=0;i < N;i...