我不明白这个错误

I dont understand this error

本文关键字：错误 明白      更新时间：2023-10-16

im当前在c 中为班级编写一个阵列包装器，我不知道我得到的错误是什么。

这些是源文件和标题文件

#include "List.h"
#include <cstdlib>
#include <stdexcept>
#include <iostream>
using namespace std;
List::List(int x){
    if(x>10){
        arrSize=x;
    }else{
        arrSize=10;
    }
    array = new int[arrSize];
}
List::List(List& list){
    array = new int[list.size()];
    arrSize = list.size();
    for(int x=0;x<arrSize;x++){
        array[x]=list[x];
    }
}
List::~List(){
    for(int x=0;x<arrSize;x++){
        if(array[x]){
            delete(&array[x]);
        }
    }
}
 int List::size(){
     return arrSize;
 }
 int& List::operator [](int& index){
     if(index>arrSize-1){
         throw out_of_range("Array Index Out of Bounds");
     }else{
         return array[index];
     }
 }
 int& List::operator [](const int& index){
     if(index>arrSize-1){
         throw out_of_range("Array Index Out of Bounds");
     }else{
         return array[index];
     }
 }
 List& List::operator +(List& list){
     List *retList = new List(list.size()+arrSize);
     for(int x=0;x<arrSize;x++){
         (*retList)[x]=array[x];
     }
     for(int x=arrSize;x<list.size()+arrSize;x++){
         (*retList)[x]=list[x];
     }
     return *retList;
 }
 void List::operator =(List& list){
     delete(array);
     arrSize=list.size();
     array = new int[arrSize];
     for(int x=0;x<arrSize;x++){
         array[x]=list[x];
     }
 }



#ifndef LIST_H_
#define LIST_H_
#include <iostream>
using namespace std;

class List{
private:
    int arrSize;
    int *array;
public:
    List(int x=10);
    List(List&);
    ~List();
    int size();
    void operator=(List&);
    List& operator+(List&);
    int& operator[](const int&);
    int& operator[](int&);
};
void operator << (ostream io,List& list){
     io << "{";
     for(int x=0;x<list.size()-1;x++){
         io << list[x] + ",";
     }
     io << list[list.size()-1]+"}";
}
#endif /* LIST_H_ */

和主

#include "List.h"
#include <iostream>
using namespace std;
int main(){
    List list;
    for(int x=0;x<10;x++){
        list[x]=x;
    }
    cout<<list;
    return 0;
}

现在这是我遇到的错误，我不明白

In file included from /usr/include/c+
+/4.8/ios:42:0,
                 from 
/usr/include/c++/4.8/ostream:38,

from /usr/include/c++/4.8/iostream:39,

     from List.h:10,
                 from 
Main.cpp:8:
/usr/include/c++/4.8/bits/ios_base.h: 
In copy constructor 
‘std::basic_ios<char>::basic_ios(const 
std::basic_ios<char>&)’:
/usr/include/c+
+/4.8/bits/ios_base.h:786:5: error: 
‘std::ios_base::ios_base(const std::ios_base&)’ 
is private
     ios_base(const ios_base&);
     ^
In 
file included from /usr/include/c+
+/4.8/ios:44:0,
                 from 
/usr/include/c++/4.8/ostream:38,

from /usr/include/c++/4.8/iostream:39,

     from List.h:10,
                 from 
Main.cpp:8:
/usr/include/c+
+/4.8/bits/basic_ios.h:66:11: error: within this 
context
     class basic_ios : public ios_base

      ^
In file included from /usr/include/c+
+/4.8/iostream:39:0,
                 from 
List.h:10,
                 from Main.cpp:8:
/usr/include/c++/4.8/ostream: In copy constructor 
‘std::basic_ostream<char>::basic_ostream(const 
std::basic_ostream<char>&)’:
/usr/include/c+
+/4.8/ostream:58:11: note: synthesized method 
‘std::basic_ios<char>::basic_ios(const 
std::basic_ios<char>&)’ first required here 

class basic_ostream : virtual public 
basic_ios<_CharT, _Traits>
           ^
Main.cpp: 
In function ‘int main()’:
Main.cpp:17:8: note: 
synthesized method 
‘std::basic_ostream<char>::basic_ostream(const 
std::basic_ostream<char>&)’ first required here 

cout<<list;
        ^
In file included from 
Main.cpp:8:0:
List.h:29:6: error:   initializing 
argument 1 of ‘void operator<<(std::ostream, 
List&)’
 void operator << (ostream io,List& list)
{
      ^

以下方式写操作员

ostream & operator << ( ostream &io, List& list ){
     io << "{";
     for(int x=0;x<list.size()-1;x++){
         io << list[x] + ",";
     }
     io << list[list.size()-1]+"}";
    return io;
}

类Ostream没有公共复制构造函数。因此，第一个参数必须具有参考类型。

也最好将第二个参数声明为常数参考

ostream & operator << ( ostream &io, const List& list ){
     io << "{";
     for(int x=0;x<list.size()-1;x++){
         io << list[x] + ",";
     }
     io << list[list.size()-1]+"}";
    return io;
}

考虑到列表的大小等于0（该语句

），该操作员有一个错误 
     io << list[list.size()-1]+"}";

无效。

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