单链表(C++)的问题

#include<iostream>
#include"stdlib.h"
using namespace std;
class adt{
private:
adt *next;
int num;
public:
void add(int a);
void print();
adt *head;
adt *last;
adt *current;
adt *newcode;
void sethead();
};
void adt::add(int a){
newcode=new adt;
newcode->num=a;
if (head->next==NULL){
head->next=newcode;
last=newcode;
}
else {
last->next=newcode;
last=newcode;
}
}
void adt::sethead(){
head=new adt;
last=head;
}
void adt::print(){
cout<<"what you input are:"<<endl;
for(current=head;current->next!=NULL;current=current->next){
cout<<current->next->num<<" ";
}
cout<<endl;
}
void main(){
int num=1;
adt temp;
temp.sethead();
cout<<"please input so

#include<iostream>
#include"stdlib.h"
using namespace std;
class adt{
private:
adt *next;
int num;
public:
void add(int a);
void print();
adt *head;
adt *last;
adt *current;
adt *newcode;
void sethead();
};

void adt::add(int a){
newcode=new adt;
newcode->num=a;
if (head->next==NULL){
head->next=newcode;
last=newcode;
last->next=NULL;
}
else {
last->next=newcode;
last=newcode;
last->next=NULL;
}
}

void adt::sethead(){
head=new adt;
last=head;
last->next=NULL;
}

void adt::print(){
cout<<"what you input are:"<<endl;
for(current=head;current->next!=NULL;current=current->next){
cout<<current->next->num<<" ";
}

cout<<endl;
}