#include<iostream>
using namespace std;
class toy{
public:
    toy(int p,int q):price(p),quan(q)

    void sum(int p,int q)
    {sum=price*quan;}
private:
    int price;
    int quan;
};

int main()
{toy A[4]={toy(12,10),toy(12,39),toy(33,20),toy(43,20)};
int i;

for(i=0;i<4;i++)

cout<<A.sum()<<endl;
return 0;}

自己找区别吧，应该说改了 5处

#include<iostream>
using namespace std;
class toy
{
public:
    toy(int p,int q):price(p),quan(q)
    {}
    
    int sum()
    {
        return price*quan;
    }
private:
    int price;
    int quan;
};

int main()
{
    int i;
    toy A[4] = {toy(12,10),toy(12,39),toy(33,20),toy(43,20)};
    
    for(i=0;i<4;i++)
        
        cout<<A[i].sum()<<endl;

    return 0;
}