函数模板问题

template <typename  T>
void swap(T &a, T &b);

int main()
{
    int i = 10;
    int j = 20;
    cout << "i, j = " << i << ", " << j << ".\n";
    cout << "using complier generated int swapper:\n";
    swap(i, j);
    cout << "now i, j = " << i << ", " << j << ".\n";
   
    double x = 24.5;
    double y = 81.7;
    cout << "x, y = " << x << ", " << y << ".\n";
    cout << "using complier generated int swapper:\n";
    swap( x, y);
    cout << "now x, y = " << x << ", " << y << ".\n";
   
    return 0;
}

template <typename T>
void swap(T &a, T &b)
{
    T temp;
    temp = a;
    a = b;
    b = temp;
}