#include <iostream>
using namespace std;

class Sample
{
private:
    int x;
    static long p;
public:
    Sample(int a)
    {
        x=a;
        p*=x;
    }
    static void print(Sample s)
    {
        cout<<"x="<<x<<",p="<<p<<endl;
    }
};

void main()
{
    Sample s1(10);
    Sample s2(15);
    Sample::print(s1);
    Sample::print(s2);
}

我想是这出问题，但不知道怎么改
static void print(Sample s)
    {
        cout<<"x="<<x<<",p="<<p<<endl;
    }

弄明白了，应该是p是静态数据，要给它个初始值，x是s的数据成员
改完后应该是这样

#include <iostream>
using namespace std;

class Sample
{
private:
    int x;
    static long p;
public:
    Sample(int a)
    {
        x=a;
        p*=x;
    }
    static void print(Sample s)
    {
        cout<<"x="<<s.x<<",p="<<p<<endl;
    }
};
long Sample::p=1;
void main()
{
    Sample s1(10);
    Sample s2(15);
    Sample::print(s1);
    Sample::print(s2);
}