Simple error log files in ASP .NET

In some circumstances, you may not be able to debug your web application to determine what exception had occurred in it. So to create an error log file is very important to keep track of the occurred exception.

In this post, I will show you how to write an error log files by using a class file (.cs).

First of all, a class called CreateLogFiles needs to be created. In this class file, add in the codes as following:

using System;
using System.IO;
using System.Text;

namespace CSharpWeb
{
    public class CreateLogFiles
    {
        private string sFormat;
        private string sTime;

        public CreateLogFiles()
        {
            sFormat = DateTime.Now.ToShortDateString().ToString()+" "+DateTime.Now.ToLongTimeString().ToString()+" --- ";
            sTime = DateTime.Now.ToString("yyyyMMdd");
        }

         public void CreateErrorLog(string strPath, string sErr)
        {
            StreamWriter sw = new StreamWriter(strPath+sTime+".txt",true);
            sw.WriteLine(sFormat + sErr);
            sw.Flush();
            sw.Close();
         }
     }
}

In your own web page, you can use this class to create error log files, namely whenever an exception is being caught, it will create an error log file with the exception error message.

The code below is an example of mine, which I will call the CreateErrorLog function when a Checking button is clicked.

private void btnCheck_Click(object sender, System.EventArgs e)
{
    try
    {
        // ...The rest of your codes here
    }
    catch(Exception ex)
    {
         CreateLogFiles Error = new CreateLogFiles();
         Error.CreateErrorLog(Server.MapPath("Logs/ErrorLog"), ex.Message);
    }
}

Fro the codes as above, I am using Try…Catch method. Whenever an exception occurs, it will get caught by the Exception method. In there, an error log files will be created and saved as a keep track.

That’s it. If you have any curious feel free to ask me. Cheers！