问C ++不能仅通过返回类型来区分过载函数

EN

using namespace std;

int leap_year(int year);


bool div(int num, int divid) {

    if (num % divid == 0)
        return true;
    else
        return false;
}

int leap_year(int year) {
    if (div(year, 400))
        return 365;
    else if (div(year, 100) & div(year, 400) == false)
        return 366;
    else
        return 365;
}

void main() {
    int year;
    cout << "Year: ";
    cin >> year;

    int result = leap_year(year);
    cout << result;
    system("pause");
}