我正在尝试为我的类实现 operator+（它必须连接来自同一类的两个对象的单链表），但程序给出错误：“lab5.exe 中 0x01351ca3 处的未处理异常：0xC0000005：访问冲突读取位置 0xcccccccc 。” 奇怪的是它正确连接，因为我在 operator+ 中返回 temp 之前正在检查它（通过 //temp.print();）。
如果您能解释一下我的错误在哪里，我将不胜感激。这是代码：
#include <iostream>
#include <cstdlib>
#include <string>
using namespace std;
class list{
struct lista
{
int num;
char* word;
lista* next;
};
lista* head;
char* name;
public:
list(char* name1){head=NULL;name=new char[strlen(name1)+1];strcpy(name,name1);}
char getChar(int key, int index);
void setChar(int key, int index, char c);
void insert(int number,char* txt);
void remove(int number);
void print();
list(const list &o);
list& operator=(const list &x);
list& operator+(list &x);
~list();
};
void list::insert(int number,char* txt){
lista* ptr,*tmp;
ptr=head;
lista* newlista=new lista;
newlista->num=number;
newlista->next=NULL;
newlista->word= new char[strlen(txt)+1];
strcpy(newlista->word,txt);
if(head==NULL){
head=newlista;
newlista->next=NULL;
}
else while(ptr!=NULL){
if(strcmp(txt,ptr->word)>=0){
if(ptr->next!=NULL && strcmp(txt,ptr->next->word)<=0)
{
tmp=ptr->next;
ptr->next=newlista;
newlista->next=tmp;
break;
}
else if(ptr->next!=NULL && strcmp(txt,ptr->next->word)>0)
ptr=ptr->next;
else
{
//next is empty
ptr->next=newlista;
break;
}
}
else{
//txt less than in 1st element
newlista->next=head;
head=newlista;
break;
}
}
return;
}
void list::print(){
cout<<name<<";"<<endl;
lista *druk;
druk=head;
while(druk!=NULL){
cout<<"txt: "<<druk->word<<" | "<<"num: "<<druk->num<<endl;
druk=druk->next;
}
cout<<endl;
return;
}
void list::remove(int number){
if(head==NULL)
return;
if(head->num==number){
lista* ptr=head;
head=head->next;
delete [] ptr->word;
delete ptr;
return;
}
lista* ptr=head;
while(ptr->next!=NULL && ptr->next->num!=number)
ptr=ptr->next;
if(ptr->next==NULL){
cout<<number<<" element not found"<<endl;
return;
}
lista* todelete=ptr->next;
ptr->next=todelete->next;
delete [] todelete->word;
delete todelete;
return;
}
list::list(const list &o)
{
lista *xtr = o.head;
head=NULL;// without it doesn't work.
lista *etr=head;// set etr on head?
while (xtr)
{
lista* ntr = new lista;
if (!ntr)
{
cerr << "list::CopyConstructor: Allocation memory failure!";
cerr << endl;
break;
}
ntr->num = xtr->num;
ntr->word= new char[strlen(xtr->word)+1];
strcpy(ntr->word,xtr->word);
ntr->next = NULL;
if (head)
etr->next = ntr;
else
head = ntr;
etr = ntr; // keep track of the last element in *this
xtr = xtr->next;
}
name = new char[strlen(o.name)+5];
strcpy(name,o.name);
strcat(name,"Copy");
}
list& list::operator=(const list &x)
{
if(this==&x)
return *this;
lista *etr=head;
while(etr) // removing list from this
{
etr=etr->next;
delete head;
head=etr;
}
lista *xtr=x.head;
while(xtr)
{
int copied=xtr->num;
lista *ntr= new lista;
ntr->word=new char[strlen(xtr->word)+1];
if (!ntr)
{
cerr << "list::operator=: Allocation memory failure!" << endl;
break;
}
ntr->num=copied;
strcpy(ntr->word,xtr->word);
ntr->next=NULL;
if (!head)
head = ntr;
else
etr->next = ntr;
etr = ntr; // keep track of the last element in *this
xtr = xtr->next;
}
char *name=new char[strlen(x.name)+1];
strcpy(name,x.name);
return *this;
}
list::~list()
{
cout<<"Object with name:"<<name<<" destroyed!"<<endl;
delete [] name;
lista *dtr=head;
while(dtr) // removing lista from this
{
dtr=dtr->next;
delete [] head->word;
delete head;
head=dtr;
}
}
list& list::operator+(list &x)
{
list temp(this->name);
temp=*this;// using previously made operator= which creates the deep copy of singly linked list from this into temp;
lista *xtr=x.head;
while(xtr)
{
temp.insert(xtr->num,xtr->word);
xtr=xtr->next;
}
//temp.print();
return temp;
}
int main(){
list l1("lista1");
l1.insert(5,"Endian");
l1.insert(7,"Endianness");
l1.insert(100,"Hexediting");
l1.insert(34,".mil");
l1.print();
list l2(l1); // usage of CC - the same as list l2=l1;
l2.print();
l2.remove(5);
l2.print();
l1.print();
list l3("asajnment");
l3=l2=l1;
l3.print();
list l4("Testing+");
l4.insert(155,"+++++++");
l4.insert(144,"-----");
l4.insert(111,"lalala");
l4.print();
l1=l4+l3;
l1.print();
getchar();
return 0;
}