/*---------------------------------
    array2d.c -- 处理二维数组的函数
---------------------------------*/

#include <stdio.h>
#define ROWS 3
#define COLS 4

void sum_rows(int ar[][COLS], int rows);
void sum_cols(int [][COLS], int);
int sum2d(int (*ar)[COLS], int rows);

int main()
{
    int junk[ROWS][COLS] =
    {
        {2, 4, 6, 8},
        {3, 5, 7, 9},
        {12, 10, 8, 6}
    };

    sum_rows(junk, ROWS);
    sum_cols(junk, ROWS);
    printf("Sum of all elements = %d\n", sum2d(junk, ROWS));

    return 0;
}

void sum_rows(int ar[][COLS], int rows)
{
    for (int r(0); r != rows; ++r)
    {
        int total(0);
        for (int c(0); c != COLS; ++c)
            total += ar[r][c];
        printf("row %d: sum = %d\n", r, total);
    }
}

void sum_cols(int ar[][COLS], int rows)
{
    for (int c(0); c != COLS; ++c)
    {
        int total(0);
        for (int r(0); r != rows; ++r)
            total += ar[r][c];
        printf("col %d: sum = %d\n", c, total);
    }
}

int sum2d(int ar[][COLS], int rows)
{
    int total(0);

    for(int r(0); r != rows; ++r)
        for(int c(0); c != COLS; ++c)
            total += ar[r][c];

    return total;
}