<分区>
我获取了一个免费的版权模板代码并根据自己的需要进行了修改，但仍在努力使其发挥作用。如果能帮助我理解，我将不胜感激。
问题是我真的不明白重载是如何工作的，尤其是与 >> 运算符一起工作，如下例所示。为什么要返回对象 logger在 friend &operator 函数中。我不明白如何制作void print();重载工作和与 friend 互动operator << .
这是示例代码:
#pragma once
#include <fstream>
namespace Log{
class LogFile {
public:
enum class logType { LOG_ALWAYS=0, LOG_OKAY, LOG_ERROR, LOG_WARNING, LOG_INFO};
enum class writeType {FOUT=0, CFOUT, FCOUT, COUT};
explicit LogFile(string fname = "[nameError]log.txt") : numWarnings(0U), numErrors(0U)
{
myFile.open(fname);
if (myFile.is_open())
std::cout << "Log file was created successfully!" << std::endl << std::endl;
else
{
std::cout << "Fatal Error can't create log file!" << std::endl << "Please check Application permissions" << std::endl;
exit(1);
}
}
~LogFile()
{
if (myFile.is_open())
{
myFile << std::endl << std::endl;
myFile << numWarnings << " warnings" << std::endl;
myFile << numErrors << " errors" << std::endl;
myFile.close();
}
}
friend LogFile &operator << (LogFile &logger, const logType e_logtype)
{
//TO DO
//logger.myFile << tm << "| " << memUsed << "kb added|";
//<< "000000.000 | 0.0000kb added |"
switch (e_logtype)
{
case LogFile::logType::LOG_ALWAYS:
logger.myFile << " ALWAYS| ";
break;
case LogFile::logType::LOG_OKAY:
logger.myFile << " OKAY| ";
break;
case LogFile::logType::LOG_ERROR:
logger.myFile << " ERROR| ";
++logger.numErrors;
break;
case LogFile::logType::LOG_WARNING:
logger.myFile << " WARN| ";
++logger.numWarnings;
break;
default:
logger.myFile << " INFO| ";
break;
}
return logger;
}
friend LogFile &operator << (LogFile &logger, const char* text)
{
logger.myFile << tex t << std::endl;
return logger;
}
LogFile(const LogFile &) = delete;
LogFile &operator= (const LogFile &) = delete;
//THIS IS MY PART
friend void print(LogFile &logger, const char* text, const logType e_logtype, const writeType e_writetype)
{
switch (e_writetype)
{
case LogFile::writeType::FOUT:
logger << LogFile::logType::e_logtype << text;
break;
case LogFile::writeType::FCOUT:
case LogFile::writeType::CFOUT:
std::cout << text << std::endl;
logger << LogFile::logType::e_logtype << text;
break;
case LogFile::writeType::COUT:
default:
std::cout << text << std::endl;
break;
}
return;
}
private:
std::ofstream myFile;
unsigned int numWarnings;
unsigned int numErrors;
};
}
想法是将它用作标题，并在 main.cpp 中使用以下方法记录所有内容:
using namespace Log;
LogFile mylog;
mylog.print("Test...", LOG_OKAY, FCOUT);
地点:
LOG_OKAY, LOG_ERROR, etc - types of log info.
COUT, FCOUT, CFOUT, FOUT - log to file or cout or both
已编辑:我在 3 周前解决了这个问题。感谢@zenith 的回答。如果问题再次打开，我会发布带有概述代码的解决方案，我已经更改了指向它们的点。谢谢 :)