编程实现求二维数组各元素中正数元素之和与平均值,并输出。答:int n_row=3,n_col=4, i, j, k;int **a;// int a[3][4]={1,2,3,4,7,8,9,6,-10,10,-5,2};int v_max,iv,jv;int sum;printf("input n_row n_col 3 4\n");scanf("%d %d",&n_row,&n_col);a = (int **) malloc(sizeof(int *) * n_row);for (j=0...