值传递和地址传递

#include <iostream>
void fun1(int* param)
{
    *param = *param + 1;
}
void fun2(int param)
{
    param = param + 1;
}
int main()
{
    int x = 42;
    int y = 42;
    fun1(&x);
    std::cout << x << std::endl;
    std::cout << y;
}