a simple log, useing c++11

main.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <chrono>
#include <ctime>

class FLog{
public:
  FLog(std::string logfile);
  
  void info(std::string tag, std::string msg);
private:
  void writeLog(std::string type, std:: string msg);
  void rotateLog();
  bool fileExist(std::string &filename);
  void moveFile(std::string src, std::string dest);
  
  std::string m_Logfile;
  int m_numLogs;   // 5 default
  bool m_showTime; //true as default
};

FLog::FLog(std::string logfile):m_Logfile(logfile){
  m_showTime = true;
  m_numLogs = 5;
  rotateLog();
}

void FLog::info(std::string tag, std::string msg){
  std::string logmsg;
  logmsg.append(tag);
  logmsg.append(" - ");
  logmsg.append(msg);
  writeLog("I", logmsg);
}


void FLog::writeLog(std::string type, std:: string msg){
  std::ofstream of;
  of.open(m_Logfile, std::ios::app);
  if(m_showTime){
    std::chrono::system_clock::time_point currentTime = std::chrono::system_clock::now();
    time_t tt = std::chrono::system_clock::to_time_t(currentTime);
    std::string timeString = std::ctime(&tt);
    timeString.erase(timeString.end()-1, timeString.end()); //tarbort newline
    of << type << " " << timeString << " " << msg << std::endl;
  }else{
    of << type << " " << msg << std::endl;
  }
  of.close();
}

void FLog::rotateLog(){
  std::string srcLog;
  std::string destLog;
  if(fileExist(m_Logfile)){
    for(int i = m_numLogs-1; i > 0; --i){
      srcLog = m_Logfile;
      destLog = m_Logfile;
      srcLog.append(".");
      int l = i-1;
      srcLog.append(std::to_string(l));
      destLog.append(".");
      destLog.append(std::to_string(i));
      if(fileExist(srcLog)){
        moveFile(srcLog, destLog);
      }
      srcLog.clear();
      srcLog.clear();
    } 
    moveFile(m_Logfile, "./messages.log.0");
  }else{
    std::cout << "No rotate." << std::endl;
  }
}

bool FLog::fileExist(std::string &filename){
  std::ifstream ifile(filename);
  return ifile;
}

void FLog::moveFile(std::string src, std::string dest){
  int result = std::rename( src.c_str(), dest.c_str() );
  if ( result != 0 ){
    std::perror( "Error renaming file" );
  }
}


int main(){
  std::cout << "*** STARTING APP ***" << std::endl;
  FLog Log("./messages.log");
  auto start = std::chrono::steady_clock::now();
  for(int i = 0; i < 100000; i++){
    Log.info("TEST", "Hello, world!");
  }
  
  auto end = std::chrono::steady_clock::now();
  auto diff = end - start;
  std::cout << "Time: " << std::chrono::duration<double, std::milli>(diff).count() << " miliseconds" << std::endl;
  std::cout << "***** EXIT APP *****" << std::endl;
  return 0;
}