enter your score and get average score...

#include<iostream>
using namespace std;

const int ARSIZE = 10;

void show_mark(float s)
{
    cout << "Your average score is: "<< s << endl;
}

float avg(float arg[], int n)
{
    float sum = 0;
    for (int i = 0; i < n; i++)
        sum += arg[i];
    return sum/n;
}

int main()
{
    float mark[ARSIZE];
    float score;
    float total = 0;
    for (int i = 0; i < ARSIZE; i++)
    {
        cout <<"Please enter #" << i + 1 << " mark: "<< endl;
        cin >> score;
        if(!cin)
        {
            cin.clear();
            if(cin.get() != '\n')
                continue;
            cout << "Bad input! Please enter your mark correctly." << endl;
            break;
        }
        else if(mark[i] < 0)
            break;
        mark[i] = score;
    }

    total = avg(mark, ARSIZE);
    show_mark(total);
    return 0;
}

只是自己练个熟练度，大神们不要点开，免得瞎眼睛。。。