错误：'std :: ios_base :: ios_base（const std :: ios_base&）'是私有的 [英] error: ‘std::ios_base::ios_base(const std::ios_base&)’ is private

问题描述

#include <iostream>
#include <fcntl.h>
#include <fstream>

using namespace std;

 class Logger
 {
    private:
            ofstream debug;
            Logger()
            {
                    debug.open("debug.txt");
            }
            static Logger log;
    public:
            static Logger getLogger()
            {
                    return log;
            }

            void  writeToFile(const char *data)
            {
                    debug << data;
            } 

            void close()
            {
                    debug.close();
            }               
};

Logger Logger::log;

通过这个类，我试图创建一个登录到文件的Logger类。但它给出错误像

Through this class i m trying to create a Logger class which logs into a file. But it gives error like

error: ‘std::ios_base::ios_base(const std::ios_base&)’ is private

我googled它，发现它是因为复制流。根据我的理解，在这段代码没有复制的流发生。

i googled it and found that its because of copying ofstreams. As far as i understand in this code no copying of ofstreams is taking place.

可以帮助我。
提前感谢。

Can u guys help me out. Thanks in advance.

〜

推荐答案

static Logger getLogger()
{
   return log;
}

尝试返回记录器 by value，这需要一个复制构造函数。编译器生成的复制构造函数试图创建成员 debug 的副本。

attempts to return a Logger by value, which requires a copy-constructor. The compiler-generated copy-constructor attempts to make a copy of the member debug. Which is why you get the error.

你可以实现一个复制构造函数（可能没有意义，因为 debug 成员将不同）或通过引用返回：

You can either implement a copy constructor (probably doesn't make sense, since the debug member would be different) or return by reference:

static Logger& getLogger()
{
   return log;
}

这是安全的，因为 log 有静态存储持续时间。

正确的调用如下所示：

Logger& l = Logger::getLogger();

在这种情况下 l 指 Logger :: log 。

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