形参里带取地址符号

void swap(int &a, int& b)
{
    int temp;
    temp = a;
    a = b;
    b = temp;
    std::cout << " swap a = "<< a << std::endl;
}
 
int main()
{
    int a = 1, b = 2;
    swap(a,b);
    std::cout << " main a = "<< a << std::endl;
}

结果为  swap a = 2
             main a = 2

void swap(int a, int b)
{
    int temp;
    temp = a;
    a = b;
    b = temp;
    std::cout << " swap a = "<< a << std::endl;
}
 
int main()
{
    int a = 1, b = 2;
    swap(a,b);
    std::cout << " main a = "<< a << std::endl;
}

 结果为swap a = 2
            main a = 1

形参不带取地址符是赋值了临时新变量

带了取地址符是直接用之前的变量