编写一个程序，输入三个整数，将它们按照由大到小的顺序输出。要求：输入输出语句在主函数中，排序使用自定义函数，必须用到变量的引用。

#include <iostream>
using namespace std;

void sort(int& a, int& b, int& c) {
    int temp;
    if (a < b) {
        temp = a;
        a = b;
        b = temp;
    }
    if (a < c) {
        temp = a;
        a = c;
        c = temp;
    }
    if (b < c) {
        temp = b;
        b = c;
        c = temp;
    }
}

int main() {
    int a, b, c;
    cout << "请输入三个整数：";
    cin >> a >> b >> c;
    sort(a, b, c);
    cout << "按照由大到小的顺序输出：";
    cout << a << " " << b << " " << c << endl;
    return 0;
}