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C++ Code Snippet
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A Powerful Easy-To-Read Logging System

by 1o0oBhP on Dec 19th, 2004

Log files are useful things. They are used in programs to display the values or variables or other useful information such as what the program is doing. This is useful is the program crashes at some point or is not behaving as it should. By writing values and events to a log you can check back and see what happened! Most logs are text files, which take a while to search though and arent very easy to debug. HTML files however support different colours for different events (ie green text if it worked, red if its an error....) and images (so you can dump screenshots ect). The following code forms the basis to create a log file in HTML which has icons and font colours to show what type of event happened and also is tabulated so it is easy to read.
To make it work you need 3 bmps to use as icons (i recommend 16x16). I have files for download, check in the main forums. Run it and look at the resulting HTML file. Enjoy!

C++ Code Snippet (Toggle Plain Text)

#include <fstream>
#include <string>
 
#define APP_NAME    "Program name"
#define COMPANY_NAME "CompanyX"
 
#define NORMAL_COLOUR    "#0000FF" // Blue
#define WARNING_COLOUR   "#FF8000" // orange
#define ERROR_COLOUR     "#FF0000" // red  
 
using namespace std;
string logfile = "log.html";
bool logisopen = 0;
 
void OpenLog(void)
{
    if(!logisopen)
    {
        string str = "<html>\n<head>\n<title>";
        str += APP_NAME;
        str += " Logging system &copy";
        str += COMPANY_NAME;
        str += "</title>\n</head>\n<body>\n<table>\n<caption><b>";
        str += "LOG ENTRIES</b></caption>";
 
        fstream file;
        file.open(logfile.c_str(), ios::out | ios::trunc);
        file.seekp(0, ios::beg);
        file.write(str.c_str(), str.length());
        file.close();
 
        logisopen = 1;
    }    
}
 
void AddNormalEntryToLog(char* text)
{
    if(logisopen)
    {
        string str = "<tr><td><img src=\"log_ok.bmp\"></td><td>";
        str += "<font color=\"";
        str += NORMAL_COLOUR;
        str += "\"><b>";
        str += text;
        str += "</b></font></td></tr>";
 
        fstream file;
        file.open(logfile.c_str(), ios::app | ios::out);
        file.write(str.c_str(), str.length());
        file.close();
    }    
}
void AddWarningEntryToLog(char* text)
{
    if(logisopen)
    {
        string str = "<tr><td><img src=\"log_warning.bmp\"></td><td>";
        str += "<font color=\"";
        str += WARNING_COLOUR;
        str += "\"><b>";
        str += text;
        str += "</b></font></td></tr>";
 
        fstream file;
        file.open(logfile.c_str(), ios::app | ios::out);
        file.write(str.c_str(), str.length());
        file.close();
    } 
}
void AddErrorEntryToLog(char* text)
{
    if(logisopen)
    {
        string str = "<tr><td><img src=\"log_error.bmp\"></td><td>";
        str += "<font color=\"";
        str += ERROR_COLOUR;
        str += "\"><b>";
        str += text;
        str += "</b></font></td></tr>";
 
        fstream file;
        file.open(logfile.c_str(), ios::app | ios::out);
        file.write(str.c_str(), str.length());
        file.close();
    } 
}
 
void CloseLog(void)
{
    if(logisopen)
    {
        string str = "</table>\n</body>\n</html>";
 
        fstream file;
        file.open(logfile.c_str(), ios::out | ios::app); 
        file.write(str.c_str(), str.length());
        file.close();
    }
 
    logisopen = 0;
}
 
int WINAPI WinMain (HINSTANCE hThisInstance,
                    HINSTANCE hPrevInstance,
                    LPSTR lpszArgument,
                    int nFunsterStil)
 
{
 
    char this_path[MAX_PATH];
	char log_txt[MAX_PATH];
    HINSTANCE hInstance = GetModuleHandle(NULL);
	GetModuleFileName(hInstance, this_path, MAX_PATH);
    strcat(log_txt, "Program started. EXE = ");
    strcat(log_txt, this_path);
 
    OpenLog();
    AddNormalEntryToLog(log_txt);
    AddNormalEntryToLog("Registered Window Class");
    AddWarningEntryToLog("WARNING: Could not load data!");
    AddWarningEntryToLog("WARNING: Virtual Memory Low");
    AddErrorEntryToLog("ERROR: Could not initialise DirectX");
 
    CloseLog();
    return 0;
}

#include <fstream>
#include <string>

#define APP_NAME    "Program name"
#define COMPANY_NAME "CompanyX"

#define NORMAL_COLOUR    "#0000FF" // Blue
#define WARNING_COLOUR   "#FF8000" // orange
#define ERROR_COLOUR     "#FF0000" // red  

using namespace std;
string logfile = "log.html";
bool logisopen = 0;

void OpenLog(void)
{
    if(!logisopen)
    {
        string str = "<html>\n<head>\n<title>";
        str += APP_NAME;
        str += " Logging system &copy";
        str += COMPANY_NAME;
        str += "</title>\n</head>\n<body>\n<table>\n<caption><b>";
        str += "LOG ENTRIES</b></caption>";
    
        fstream file;
        file.open(logfile.c_str(), ios::out | ios::trunc);
        file.seekp(0, ios::beg);
        file.write(str.c_str(), str.length());
        file.close();
        
        logisopen = 1;
    }    
}
    
void AddNormalEntryToLog(char* text)
{
    if(logisopen)
    {
        string str = "<tr><td><img src=\"log_ok.bmp\"></td><td>";
        str += "<font color=\"";
        str += NORMAL_COLOUR;
        str += "\"><b>";
        str += text;
        str += "</b></font></td></tr>";
        
        fstream file;
        file.open(logfile.c_str(), ios::app | ios::out);
        file.write(str.c_str(), str.length());
        file.close();
    }    
}
void AddWarningEntryToLog(char* text)
{
    if(logisopen)
    {
        string str = "<tr><td><img src=\"log_warning.bmp\"></td><td>";
        str += "<font color=\"";
        str += WARNING_COLOUR;
        str += "\"><b>";
        str += text;
        str += "</b></font></td></tr>";
    
        fstream file;
        file.open(logfile.c_str(), ios::app | ios::out);
        file.write(str.c_str(), str.length());
        file.close();
    } 
}
void AddErrorEntryToLog(char* text)
{
    if(logisopen)
    {
        string str = "<tr><td><img src=\"log_error.bmp\"></td><td>";
        str += "<font color=\"";
        str += ERROR_COLOUR;
        str += "\"><b>";
        str += text;
        str += "</b></font></td></tr>";
    
        fstream file;
        file.open(logfile.c_str(), ios::app | ios::out);
        file.write(str.c_str(), str.length());
        file.close();
    } 
}

void CloseLog(void)
{
    if(logisopen)
    {
        string str = "</table>\n</body>\n</html>";
        
        fstream file;
        file.open(logfile.c_str(), ios::out | ios::app); 
        file.write(str.c_str(), str.length());
        file.close();
    }
    
    logisopen = 0;
}

int WINAPI WinMain (HINSTANCE hThisInstance,
                    HINSTANCE hPrevInstance,
                    LPSTR lpszArgument,
                    int nFunsterStil)

{
    
    char this_path[MAX_PATH];
	char log_txt[MAX_PATH];
    HINSTANCE hInstance = GetModuleHandle(NULL);
	GetModuleFileName(hInstance, this_path, MAX_PATH);
    strcat(log_txt, "Program started. EXE = ");
    strcat(log_txt, this_path);
            
    OpenLog();
    AddNormalEntryToLog(log_txt);
    AddNormalEntryToLog("Registered Window Class");
    AddWarningEntryToLog("WARNING: Could not load data!");
    AddWarningEntryToLog("WARNING: Virtual Memory Low");
    AddErrorEntryToLog("ERROR: Could not initialise DirectX");
    
    CloseLog();
    return 0;
}

Comments on this Code Snippet

Permalink

Dec 19th, 2004

Re: A Powerful Easy-To-Read Logging System

Sorry! couldnt work out how to upload fiiles so ull have to draw some icons yourself!

1o0oBhP

Posting Pro in Training

Offline

445 posts
since Dec 2004

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Dec 19th, 2004

Re: A Powerful Easy-To-Read Logging System

This idea is good. FunsterStil sounds Dutch to me!

vegaseat

DaniWeb's Hypocrite

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5,792 posts
since Oct 2004

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Dec 20th, 2004

Re: A Powerful Easy-To-Read Logging System

Its what the DevC++ Windows Template Gave me!!! i dont actually know yet what the significance of that parameter is and its only used to show the window...

1o0oBhP

Posting Pro in Training

Offline

445 posts
since Dec 2004

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Dec 20th, 2004

Re: A Powerful Easy-To-Read Logging System

PS: This is a windows app! the three bmps you need to make should be called log_ok.bmp, log_warning.bmp and log_error.bmp. You could make these filenames #define'd constants so that someone else may change them....

1o0oBhP

Posting Pro in Training

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445 posts
since Dec 2004

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Dec 21st, 2004

Re: A Powerful Easy-To-Read Logging System

After three bottles of Dutch beer I figured it out, FunsterStil means Windows Style.

vegaseat

DaniWeb's Hypocrite

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5,792 posts
since Oct 2004

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Dec 21st, 2004

Re: A Powerful Easy-To-Read Logging System

Ah ha!! you mean whether its max/min/default! it makes sense now i should have seen it after programming a text editor and using the windows size message.....

1o0oBhP

Posting Pro in Training

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445 posts
since Dec 2004

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Jan 19th, 2005

Re: A Powerful Easy-To-Read Logging System

The logs are always good. I would not implement icons, they take a lot of resources.

Teddy

Newbie Poster

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2 posts
since Jan 2005

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Mar 23rd, 2005

Re: A Powerful Easy-To-Read Logging System

They only take up minute disk space and minimal ram on the html docs! You can always NOT provide a file, then nothing is drawn...

1o0oBhP

Posting Pro in Training

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445 posts
since Dec 2004

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Jun 17th, 2005

Re: A Powerful Easy-To-Read Logging System

I get the following error code when I try to complie this source code??? I did a straight copy and past into Dev-C++.

"103 C:\Programs I Made\Logging File through HTML.cpp `WINAPI' does not name a type"

Any ideas?

Rodan

Newbie Poster

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3 posts
since Jun 2005

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