在網上看了一些網友的答案，不是很滿意！於是自己寫了一個

#include <stdio.h>
#include <ctype.h>

void show_arr(int arr[][5], int n);

void store_date(double arr[][5]);
void average_per_row(const double arr[], int n);
void average(const double arr[][5], int len);
void find_max(const double arr[][5], int len);

int main(void)
{
	double arr[3][5] = { 0 };
	store_date(arr);
	for (int i = 0; i < 3; i++)
		average_per_row(arr[i], i+1);
	average(arr, 3);
	find_max(arr, 3);
	getchar();

	return 0;
}

void show_arr(int arr[][5], int n)
{
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < 5; j++)
			printf("%4d", arr[i][j]);
		putchar('\n');
	}
}

void store_date(double arr[][5])
{
	for (int i = 0; i < 3; i++)
		for (int j = 0; j < 5; j++)
			scanf("%lf", &arr[i][j]);
}
void average_per_row(const double arr[],int n)
{
	double avg = 0;
	for (int i = 0; i < 5; i++)
		avg += arr[i];
	avg /= 5;
	printf("The average of the %d row is %g\n", n, avg);
}
void average(const double arr[][5], int len)
{
	double avg = 0;
	for (int i = 0; i < len; i++)
		for (int j = 0; j < 5; j++)
			avg += arr[i][j];
	avg = avg / (len * 5);
	printf("The average of the data is %g\n", avg);
}
void find_max(const double arr[][5], int len)
{
	double max = arr[0][0];
	for (int i = 0; i < len; i++)
		for (int j = 0; j < 5; j++)
			max = max > arr[i][j] ? max : arr[i][j];
	printf("The maximun of the data is %g\n", max);
}