集合类运算符重载c++，运行结果不正确

```c++
#include<iostream>
using namespace std;
class set{
    public:
        set(){
         pelem=NULL;
         count=0;
        }
        set(const set& s1){
            count=s1.count;
            pelem=new int[count];
            for(int i=0;i<count;i++)
            *(pelem+i)=*(s1.pelem);
        }
        void print();
        set(int *a,int num){
            count=num;
            pelem=new int[count];
            for(int i=0;i<count;i++)
                pelem[i]=a[i];
        }
        set operator +(const set& s1);
        set operator -(const set& s1);
        set operator *(const set& s1);
        void operator =(const set& s1);
        bool exist(int x); 
        ~set(){
            count=0;
            delete []pelem;
        }
    private:
        int* pelem;
        int count;
};

void set::print(){
        for(int i=0;i<count;i++){
            cout<<pelem[i];
            if(i<count-1)
            cout<<" ";
        }
        cout<<endl;
}
bool set::exist(int x){
    for(int i=0;i<count;i++){
        if(pelem[i]==x)
        return true;
    }
    return false;
}
void set::operator =(const set& s2){
    count=s2.count;
    pelem=new int[count];
    for(int i=0;i<count;i++)
        pelem[i]=s2.pelem[i];
}
set set::operator +(const set& s1){
    set s;
    s.count=s1.count; 
    s.pelem=new int [count+s1.count];
    for(int i=0;i<s.count;i++)
        s.pelem[i]=s1.pelem[i];
    for(int i=0;i<count;i++){
        if(!s.exist(pelem[i])){
            s.pelem[count]=pelem[i];
            s.count++;
        }
    }
    return s;
}
set set::operator -(const set& s1){
    set s;
    s.count=count;
    s.pelem=new int [count];
    for(int i=0;i<count;i++)
        s.pelem[i]=pelem[i];
    for(int i=0;i<s1.count;i++){
            if(s.exist(s1.pelem[i])){
                for(int k=i;k<count;k++){
                    s.pelem[k+1]=s.pelem[k];
                }
                
                s.count--;
            }
        }
    return s;
}
set set::operator *(const set& s1){
    set s;
    s.pelem=new int [count];
    s.count=0;
    for(int i=0;i<count;i++){
            if(exist(s1.pelem[i])){
                s.pelem[i]=s1.pelem[i];
                s.count++;
            }
        }
    return s;
}

int main(){
    int b[5]={1,3,5,7,9};
    int c[3]={1,4,6};
    set A(b,5);
    set B(c,3);
    cout<<"集合A：";
    A.print();
    cout<<"集合B：";
    B.print();
    set C=A+B;
    cout<<"A+B=";
    C.print();
    C=A-B;
    C.print();
    C=A*B;
    C.print();
    
    return 0;
}

```

自己不会设断点或单步调试吗？

operator= 应该返回set&