A Text File Logging system for use in VC++ projects


Environment: This code was compiled and tested with Visual C++ 6.0

In many applications it is necessary to have a logging system which logs text into a file.The following class provides such a logging system which is very easy to use.

The features include

1. Logging of text directly / using string table ids

2. Tracking of log file size (displays warning messages without affecting further logging)

3. automatically provides date and time with the log message

4. ablility to clear the log file etc..

How does the output text file look like ?

format is Date    Time    Logged text

For Example:

01/17/99 17:02:46 Here goes ur text

How do I integrate it with my existing code or how do I use it?

Just add the two files into ur project and in the appclass or ur project create an object like this

In the header (.h) file

#include "log.h"

class CSomeApp : public CWinApp
 CLog m_Log;


In the implementation (.cpp) file

CSomeApp::CSomeApp():m_Log("log file name") // see log
constructor for more details
 // TODO: add construction code here

and where ever you want to log u can use code like this...

extern CSomeApp theApp;
theApp.m_Log.LogMessage("this is what is logged");    // see

LogMessage for more details

or you can use these macros

// macro to log a string directly

#ifndef LOGS
 #define LOGS(sz) ((CSomeApp*)AfxGetApp())->m_Log.LogMessage(sz)

// macro to log  a string using a  string table id
#ifndef LOGN
 #define LOGN(a) ((CSomeApp*)AfxGetApp())->m_Log.LogMessage(a)

Download source - 3 KB


  • This code will fail if Program crashes in middle.

    Posted by Legacy on 02/03/1999 12:00am

    Originally posted by: Shashik

    This object will fail to close the log file, and thus all the details that were entered in the log file will be lost, if the application crashes in between. I think it would work if you open file in append mode and log the message, and as it is close the file. Just let me know whether I'm right.
    Thank you.

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