4．下列程序的输出结果是（　　）。

#include <iostream>
using namespace std;
void f(int a, int b) {
    int t = a;
    a = b;
    b = t;
    cout << a << "," << b << ";";
}
int main() {
    int a = 2, b = 8;
    f(a, b);
    cout << a << "," << b;
    return 0;
}