C++ C++；类中的ifstream错误

我搜索了很多关于这个问题的地方，发现了很多类似的问题，但我没有找到解决方案。我正在声明一个类：

class File {

    public:
            string fileName;
            std::ifstream & flinstream;
            Password pass;
            //Next block to look at
            unsigned int nb;
            unsigned int sectorsLeft;
File (string name,string passd);
File ( );
};

以及相应的函数：

File::File (string name,string passd) {
         fileName =  name;
        const char* cstr =  name.c_str();
         pass =  Password(passd);
         flinstream =  std::ifstream(cstr);
        if(!flinstream.good()) {
            string err =  "The file '";
            err.append(name);
            err.append("' could not be opened!");
            callError(err,3);
        }
    }

在编译时，我得到以下错误：

 [0] => out.cpp: In constructor ‘File::File(std::string, std::string)’:
    [1] => out.cpp:130:3: error: uninitialized reference member ‘File::flinstream’
    [2] => In file included from /usr/include/c++/4.5/ios:39:0,
    [3] =>                  from /usr/include/c++/4.5/ostream:40,
    [4] =>                  from /usr/include/c++/4.5/iostream:40,
    [5] =>                  from out.cpp:1:
    [6] => /usr/include/c++/4.5/bits/ios_base.h: In member function ‘std::basic_ios<char>& std::basic_ios<char>::operator=(const std::basic_ios<char>&)’:
    [7] => /usr/include/c++/4.5/bits/ios_base.h:788:5: error: ‘std::ios_base& std::ios_base::operator=(const std::ios_base&)’ is private
    [8] => /usr/include/c++/4.5/iosfwd:77:11: error: within this context
    [9] => /usr/include/c++/4.5/iosfwd: In member function ‘std::basic_istream<char>& std::basic_istream<char>::operator=(const std::basic_istream<char>&)’:
    [10] => /usr/include/c++/4.5/iosfwd:83:11: note: synthesized method ‘std::basic_ios<char>& std::basic_ios<char>::operator=(const std::basic_ios<char>&)’ first required here
    [11] => /usr/include/c++/4.5/iosfwd: In member function ‘std::basic_ifstream<char>& std::basic_ifstream<char>::operator=(const std::basic_ifstream<char>&)’:
    [12] => /usr/include/c++/4.5/iosfwd:111:11: note: synthesized method ‘std::basic_istream<char>& std::basic_istream<char>::operator=(const std::basic_istream<char>&)’ first required here
    [13] => /usr/include/c++/4.5/streambuf: In member function ‘std::basic_filebuf<char>& std::basic_filebuf<char>::operator=(const std::basic_filebuf<char>&)’:
    [14] => /usr/include/c++/4.5/streambuf:781:7: error: ‘std::basic_streambuf<_CharT, _Traits>::__streambuf_type& std::basic_streambuf<_CharT, _Traits>::operator=(const std::basic_streambuf<_CharT, _Traits>::__streambuf_type&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_streambuf<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]’ is private
    [15] => /usr/include/c++/4.5/iosfwd:108:11: error: within this context
    [16] => /usr/include/c++/4.5/iosfwd: In member function ‘std::basic_ifstream<char>& std::basic_ifstream<char>::operator=(const std::basic_ifstream<char>&)’:
    [17] => /usr/include/c++/4.5/iosfwd:111:11: note: synthesized method ‘std::basic_filebuf<char>& std::basic_filebuf<char>::operator=(const std::basic_filebuf<char>&)’ first required here
    [18] => out.cpp: In constructor ‘File::File(std::string, std::string)’:
    [19] => out.cpp:134:36: note: synthesized method ‘std::basic_ifstream<char>& std::basic_ifstream<char>::operator=(const std::basic_ifstream<char>&)’ first required here
    [20] => out.cpp: In constructor ‘File::File()’:
    [21] => out.cpp:142:3: error: uninitialized reference member ‘File::flinstream’
    [22] => out.cpp: In member function ‘File& File::operator=(const File&)’:
    [23] => out.cpp:51:12: error: non-static reference member ‘std::ifstream& File::flinstream’, can't use default assignment operator
    [24] => out.cpp: In function ‘int main(int, char**)’:
    [25] => out.cpp:166:57: note: synthesized method ‘File& File::operator=(const File&)’ first required here
)

以及使用建议的

open（）

函数：

flinstream.open(cstr);

---

但是，错误仍然是一样的。

对于初学者来说，除非您真的想要引用

ifstream

，否则我将在您的类中将

ifstream

声明为

std::ifstream flinstream;

在C++03（C++的早期版本）中，流类的赋值被禁用，因此

flinstream =  std::ifstream(cstr);

不会编译。但是，您可以使用

std:：ifstream:：open

方法执行以下操作：

flinstream.open(cstr);
/* ... remaining processing ... */

---

希望这有帮助

引用不能保持未初始化状态。必须初始化初始值设定项列表中的所有引用成员

正在构造函数体中初始化flinstream。在构造函数主体执行时，flinstream的值必须具有合法值。引用必须始终具有法律价值

---

初始值设定项列表应始终优先于构造函数主体。

@preducer-Ah！我知道发生了什么事。由于类的字段是

ifstream

，因此无法复制或分配类的实例，因为

ifstream

不支持复制。您真的需要

ifstream

作为字段吗？如果是这样，你真的需要能够复制你的类吗？这是非常必要的。有没有办法让我的编译器不情愿地复制它，或者我应该制作一个ifstreams的二级数组来补充类（因此它们不在类中，只是在一个大小相同的数组中）？@preducer-我会首先找出你在哪里制作副本，然后看看是否有必要。如果是，那么您应该定义自己的复制构造函数和赋值运算符，以便每次都可以手动重新打开该文件。@preducer:您可以使用

std:：ifstream*

并使用智能指针类，也可以自己管理内存分配。可以毫无问题地复制指针。@templatetypedef，我只是初始化了一个充满File类的大型全局数组，到目前为止我已经完成了所有的工作。

flinstream.open(cstr);
/* ... remaining processing ... */