在Array模板中重载<<和>>的问题

[elegant87]

//下面的程序在Dev_C++上编译通不过！
//提示: [Warning] friend declaration `std::ostream& operator<<(std::ostream&, Array<T>&)' declares a 
//[Warning] (if this is not what you intended, make sure the function template has already been declared and add <> after the function name here) -Wno-non-template-friend disables this warning 
non-template function 


#include <iostream>
#include <cstdlib>

using namespace std;

template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
        friend ostream& operator <<(ostream&, Array<T>&); 
        friend istream& operator >>(istream& ,Array<T>&); 
private: 
        T *array; 
        int size ; 
}; 

template <class T> 
Array<T>::Array(int len) 
{ 
        array=new T[len]; 
        size=len; 
} 

template <class T> 
Array<T>::~Array() 
{ 
       delete[]array; 
       size=0; 
} 

template <class T> 
ostream& operator <<(ostream& out,Array<T>& a) 
{ 
      cout<<"the all number is :"<<endl; 
      for(int i=0;i<a.size;i++) 
      { 
          out<<a.array[i]<<ends; 
      } 
      return out; 
} 

template <class T> 
istream& operator >>(istream& in ,Array<T>& a) 
{ 
      for(int i=0;i<a.size;i++) 
      { 
           cout<<"input the "<<(i+1)<<" number"<<endl; 
           in>>a.array[i]; 
      } 
      return in; 
} 

int main() 
{ 
    Array<int>IA(6);
    cin>>IA;
    cout<<IA<<endl;
    system("PAUSE");
    return EXIT_SUCCESS;

}

//我把头文件修改了一下！在VC6.0上成功运行!
//大家看看这是怎么回事嗯？
//我想用Dev_C++编译器，怎么修改呢？

#include <iostream.h>
#include <stdlib.h>

template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
        friend ostream& operator <<(ostream&, Array<T>&); 
        friend istream& operator >>(istream& ,Array<T>&); 
private: 
        T *array; 
        int size ; 
}; 

template <class T> 
Array<T>::Array(int len) 
{ 
        array=new T[len]; 
        size=len; 
} 

template <class T> 
Array<T>::~Array() 
{ 
       delete[]array; 
       size=0; 
} 

template <class T> 
ostream& operator <<(ostream& out,Array<T>& a) 
{ 
      cout<<"the all number is :"<<endl; 
      for(int i=0;i<a.size;i++) 
      { 
          out<<a.array[i]<<ends; 
      } 
      return out; 
} 

template <class T> 
istream& operator >>(istream& in ,Array<T>& a) 
{ 
      for(int i=0;i<a.size;i++) 
      { 
           cout<<"input the "<<(i+1)<<" number"<<endl; 
           in>>a.array[i]; 
      } 
      return in; 
} 

int main() 
{ 
    Array<int>IA(6);
    cin>>IA;
    cout<<IA<<endl;
    system("PAUSE");
    return EXIT_SUCCESS;

}

[太乙]

只是警告而已嘛！

要不把错误贴出来！

[lzr4304061988012]

//这个以前讨论过几次；

//方法一：
templat <class T> Array;
template<class T> ostream & operator <<(ostream &,Array<T> &);
template<class T> istream & operator >>(istream& ,Array<T>&); 
template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
        friend ostream& operator <<(ostream&, Array<T>&); 
      {
    cout<<"the all number is :"<<endl; 
      for(int i=0;i<a.size;i++) 
      { 
          out<<a.array[i]<<ends; 
      } 
      return out; 
   } 

friend istream& operator >>(istream& in ,Array<T>& a) 
{ 
      for(int i=0;i<a.size;i++) 
      { 
           cout<<"input the "<<(i+1)<<" number"<<endl; 
           in>>a.array[i]; 
      } 
      return in; 
} 
 
private: 
        T *array; 
        int size ; 
}; 
.......

//方法二；
template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
        friend ostream& operator <<(ostream&, Array<T>&)
          {
               
        friend istream& operator >>(istream& ,Array<T>&); 
private: 
        T *array; 
        int size ; 
}; 

[lzr4304061988012]

//方法二没贴出来；
template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
        friend ostream& operator <<(ostream&, Array<T>&)
         {......//定义；}
                         
               
        friend istream& operator >>(istream& ,Array<T>&); 
         {.....//dingyi;}
private: 
        T *array; 
        int size ; 
}; 

[lzr4304061988012]

//再贴一遍方法一，刚刚帖错了；晕死；
templat <class T> Array;
template<class T> ostream & operator <<(ostream &,Array<T> &);
template<class T> istream & operator >>(istream& ,Array<T>&); 
template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
       friend ostream& operator <<(ostream&, Array<T>&); 
     
friend istream& operator >>(istream& in ,Array<T>& a) ；
 
private: 
        T *array; 
        int size ; 
}; 
.......

[星羽]

//下面的程序在Dev_C++上编译通不过！
//提示: [Warning] friend declaration `std::ostream& operator<<(std::ostream&, Array<T>&)' declares a
//[Warning] (if this is not what you intended, make sure the function template has already been declared and add <> after the function name here) -Wno-non-template-friend disables this warning
non-template function


----------

是warning 不是error

[elegant87]

[Quote=引用 4 楼 lzr4304061988012 的回复:]
C/C++ code//再贴一遍方法一，刚刚帖错了；晕死；templat<classT>Array;
template<classT>ostream&operator<<(ostream&,Array<T>&);
template<classT>istream&operator>>(istream&,Array<T>&);
template<classT>classArray
{public:~Array();
Array(int);
friend ostream&operator<<(ostream&, Array<T>&);

friend istream&operator>>(istream&in,Array<T>&a) ；private:
T*array;intsize ; …
[/Quote]
请问一下这是什么原因呢？谢谢！

[lzr4304061988012]

方法一把该函数定义为模板函数，这个模板函数之前要申明，否则编译器不理解。

方法二把该函数当作普通函数，不过这个普通函数是随着模板类的实例化而实例化的，就是依赖模板类的，必须在类中定义.

[elegant87]

/*我按照2楼的方法，在类里面定义friend ostream& operator <<(ostream& out,const Array<T>& a); 
和friend istream& operator >>(istream& in,Array<T>& a); 是运行成功!
先面的是我在类外定义，运行就有问题了啊！
提示:
[Linker error] undefined reference to `operator>>(std::istream&, Array<int>&)' 
[Linker error] undefined reference to `operator<<(std::ostream&, Array<int> const&)' */

//大家帮忙看看吧！这个问题困惑我很久了！谢谢大家了！

#include <iostream>

using namespace std;

template <class T> class Array; 
template <class T> ostream& operator <<(ostream& out,const Array<T>& a);
template <class T> istream& operator >>(istream& in,Array<T>& a); 

template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
        T& operator[](int); 
        Array& operator =(Array<T>&); 
        friend ostream& operator <<(ostream& out,const Array<T>& a); 
        friend istream& operator >>(istream& in,Array<T>& a); 
        T FindCenter(T);   //搜索数据与定值相同的结点
private: 
        T *array; 
        int size ; 
}; 

template <class T> 
Array<T>::Array(int len) 
{ 
        array=new T[len]; 
        size=len; 
} 

template <class T> 
Array<T>::~Array() 
{ 
       delete[]array; 
       size=0; 
} 

template <class T> 
Array<T>& Array<T>::operator =(Array<T>& b) 
{ 
      if(size!=b.size) 
      { 
             cout<<"can't use equal !"<<endl; 
             abort(); 
      } 

      for(int i=0;i<size;i++) 
            array[i]=b.array[i]; 

      return *this; 
} 

template <class T> 
T& Array<T>::operator[](int len) 
{ 
      if(len<0||len>size) 
      { 
             cout<<"is out side !"; 
             abort(); 
      } 
      return array[len]; 
} 

template <class T> 
ostream& operator <<(ostream& out,const Array<T>& a) 
{ 
      cout<<"the all number is :"<<endl; 
      for(int i=0;i<a.size;i++) 
      { 
          out<<a.array[i]<<ends; 
      } 
      return out; 
} 

template <class T> 
istream& operator >>(istream& in ,Array<T>& a) 
{ 
      for(int i=0;i<a.size;i++) 
      { 
           cout<<"input the "<<(i+1)<<" number"<<endl; 
           in>>a.array[i]; 
      } 
      return in; 
} 

template<typename T> 
T Array<T>::FindCenter(T data)
{
    while(size)
    {   if(size/2==1)
        {   
            cout<<array[size/2]<<endl;
        }
        else 
        {
            cout<<array[size/2-1]<<" or "<<array[(size/2)]<<endl;     
        }
     }
}

int main() 
{ 
    Array<int>IA(6);
    cin>>IA;
    cout<<IA<<endl;
    system("PAUSE");
    return EXIT_SUCCESS;

}

[lzr4304061988012]

2L的不对我贴错了，3，4L方法LZ试过没？

[lzr4304061988012]

//LZ 8L 我看了这里改下，类里面。
 friend ostream& operator << <T> (ostream& out,const Array<T>& a); 
      friend istream& operator >> <T>(istream& in,Array<T>& a); 

[elegant87]

[Quote=引用 10 楼 lzr4304061988012 的回复:]
C/C++ code//LZ 8L 我看了这里改下，类里面。friend ostream&operator<<<T>(ostream&out,constArray<T>&a);
friend istream&operator>><T>(istream&in,Array<T>&a);
[/Quote]
改了还是一样的问题！怎么回事呢？
请你在再看看！谢谢了！

[lzr4304061988012]

//一下VS2008编译通过；

#include <iostream>

using namespace std;

template <class T> class Array; 
template <class T> ostream& operator <<(ostream& out,const Array<T>& a);
template <class T> istream& operator >>(istream& in,Array<T>& a); 

template <class T> 
class Array 
{ 
public: 
        ~Array(); 
        Array(int); 
        T& operator[](int); 
        Array& operator =(Array<T>&); 
        friend ostream& operator << <T>(ostream& out,const Array<T>& a); 
        friend istream& operator >> <T>(istream& in,Array<T>& a); 
        T FindCenter(T);   //搜索数据与定值相同的结点
private: 
        T *array; 
        int size ; 
}; 

template <class T> 
Array<T>::Array(int len) 
{ 
        array=new T[len]; 
        size=len; 
} 

template <class T> 
Array<T>::~Array() 
{ 
       delete[]array; 
       size=0; 
} 

template <class T> 
Array<T>& Array<T>::operator =(Array<T>& b) 
{ 
      if(size!=b.size) 
      { 
             cout<<"can't use equal !"<<endl; 
             abort(); 
      } 

      for(int i=0;i<size;i++) 
            array[i]=b.array[i]; 

      return *this; 
} 

template <class T> 
T& Array<T>::operator[](int len) 
{ 
      if(len<0||len>size) 
      { 
             cout<<"is out side !"; 
             abort(); 
      } 
      return array[len]; 
} 

template <class T> 
ostream& operator <<(ostream& out,const Array<T>& a) 
{ 
      cout<<"the all number is :"<<endl; 
      for(int i=0;i<a.size;i++) 
      { 
          out<<a.array[i]<<ends; 
      } 
      return out; 
} 

template <class T> 
istream& operator >>(istream& in ,Array<T>& a) 
{ 
      for(int i=0;i<a.size;i++) 
      { 
           cout<<"input the "<<(i+1)<<" number"<<endl; 
           in>>a.array[i]; 
      } 
      return in; 
} 

template<typename T> 
T Array<T>::FindCenter(T data)
{
    while(size)
    {   if(size/2==1)
        {   
            cout<<array[size/2]<<endl;
        }
        else 
        {
            cout<<array[size/2-1]<<" or "<<array[(size/2)]<<endl;     
        }
     }
}

int main() 
{ 
    Array<int>IA(6);
    cin>>IA;
    cout<<IA<<endl;
    system("PAUSE");
    return EXIT_SUCCESS;

}