这是一道编程题。题目要求 main 函数三次调用 fun，每次输入一个数组整数，最后输出这个数组中最大值、最小值、总和以及平均值。

好的，这道题比较简单，下面是代码实现：

#include <iostream>
using namespace std;

void fun(int arr[], int size) {
    int maxVal = arr[0], minVal = arr[0], sum = 0;
    for (int i = 0; i < size; i++) {
        if (arr[i] > maxVal) {
            maxVal = arr[i];
        }
        if (arr[i] < minVal) {
            minVal = arr[i];
        }
        sum += arr[i];
    }
    double avg = (double)sum / size;
    cout << "max value: " << maxVal << endl;
    cout << "min value: " << minVal << endl;
    cout << "sum: " << sum << endl;
    cout << "average: " << avg << endl;
}

int main() {
    int arr1[] = {1, 2, 3, 4, 5};
    int arr2[] = {10, 20, 30};
    int arr3[] = {-5, 0, 5, 10};

    fun(arr1, 5);
    fun(arr2, 3);
    fun(arr3, 4);

    return 0;
}

输出结果如下：

max value: 5
min value: 1
sum: 15
average: 3
max value: 30
min value: 10
sum: 60
average: 20
max value: 10
min value: -5
sum: 10
average: 2.5