简易统计计算器——C++版

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
    cout << "Please enter a series of numbers to calculate the average, "
    "median and variance of them, followed by end-of-file: " << endl;

    double x, sum = 0;
    vector<double> num;
    while (cin >> x) {
        num.push_back(x);
        sum += x;
    }

// calculate average
    vector<double>::size_type size = num.size(), mid = size / 2;
    double average = sum / size;

// calculate median
    sort(num.begin(), num.end());
    double median = (size % 2 == 0) ? (num[size] + num[size-1]) / 2 : num[mid];

// calculate variance
    double s = 0;
    for (int i = 0; i < size; i++)
        s += (num[i] - average) * (num[i] - average);
    s /= size;

    cout << "The average: " << average << endl << "The median: " << median
    << endl << "The variance: " << s << endl;
    return 0;
}