c++ 写日志通用类，可设置日志级别

Logger.h

#ifndef __LOGGER_H_
#define __LOGGER_H_

#include <iostream>
#include <atlstr.h>
#pragma warning(disable:4996)

#define LEVEL_FATAL		0
#define LEVEL_ERROR		1
#define LEVEL_WARN		2
#define LEVEL_INFO		3
#define LEVEL_VERBOSE	4
#define LEVEL_DEBUG		5

static int nLoggerLevel = LEVEL_INFO;
void SetLoggerLevel(int nLevel);
void Log(int nLevel, LPCSTR func, INT line, LPCTSTR fmt, ...);

static const char * const LOGGER_LEVEL_NAME[] = {"崩溃", "错误", "警告", "信息", "详细", "调试"};
static const char * const LOGGER_LEVEL_CODE[] = {"FATAL", "ERROR", "WARN ", "INFO ", "VERBOSE", "DEBUG"};

#define logging(nLevel, x, ...) \
	Log(nLevel,  __FUNCTION__, __LINE__, (x), __VA_ARGS__)

#define LOG_FATAL(x,...)	logging(LEVEL_FATAL,   (x), __VA_ARGS__)
#define LOG_ERROR(x,...)	logging(LEVEL_ERROR,   (x), __VA_ARGS__)
#define LOG_WARN(x,	...)	logging(LEVEL_WARN,    (x), __VA_ARGS__)
#define LOG_INFO(x,	...)	logging(LEVEL_INFO,    (x), __VA_ARGS__)
#define LOG_VERBOSE(x,...)	logging(LEVEL_VERBOSE, (x), __VA_ARGS__)
#define LOG_DEBUG(x,...)	logging(LEVEL_DEBUG,   (x), __VA_ARGS__)

#endif

Logger.cpp

#include <stdafx.h>
#include <tchar.h>
#include "Logger.h"

void SetLoggerLevel(int nLevel)
{
	if (LEVEL_DEBUG < nLevel || nLevel < LEVEL_FATAL)
	{
		LOG_WARN(_T("设置日志级别:%d 失败，默认INFO级别！"), nLevel);
		return;
	}
	nLoggerLevel = nLevel;
	LOG_INFO(_T("设置日志级别:%s 成功！"), LOGGER_LEVEL_NAME[nLevel]);
}

void Log(INT nLevel, LPCSTR func, INT line, LPCTSTR fmt, ...)
{
	if (nLevel > nLoggerLevel)
		return;

	// 设置地域，不然fprintf写不了中文
	setlocale(0, "chs");

	FILE *fp = NULL;
	TCHAR szLogFile[MAX_PATH] = {0};
	va_list args;
	va_start(args, fmt);

	GetCurrentDirectory(MAX_PATH, szLogFile);
	SYSTEMTIME sys;
	GetLocalTime( &sys );
	
	// 创建Log目录
	_stprintf_s(szLogFile, _T("%s\\log\\"), szLogFile);
	::_tmkdir(szLogFile);
	_stprintf_s(szLogFile, _T("%s\\log_%4d%02d%02d.log"), szLogFile, sys.wYear, sys.wMonth, sys.wDay);
	
	fopen_s(&fp, CW2A(szLogFile), "a+");
	if (!fp) 
	{
		TCHAR szOutput[MAX_PATH] = {0};
		char errMsg[MAX_PATH] = { 0 };
		strerror_s(errMsg, MAX_PATH, errno);
		_stprintf_s(szOutput, _T("Open run log file[%s] error: %s\n"), szLogFile, (CA2T)errMsg);
		OutputDebugString(szOutput);
		return;
	}
	fprintf(fp, "[%4d/%02d/%02d %02d:%02d:%02d.%03d][%ld:%ld][%s]", sys.wYear, sys.wMonth, sys.wDay, sys.wHour, sys.wMinute, sys.wSecond, sys.wMilliseconds,
		GetProcessId(NULL), GetThreadId(NULL), LOGGER_LEVEL_CODE[nLevel]);

	//fprintf( fp, "%s:Line%d ", func, line);
	fprintf(fp, "%s ", func);
	//_ftprintf(fp, fmt, args);
	_vftprintf_s(fp, fmt, args);
	fprintf( fp, "\n");

	fclose(fp);
	va_end(args);
}

代码经过较长时间的测试，可用性高。