C# Logging: Complete Guide to Logging Best Practices and Implementation

Logging in C# is the process of recording application events, errors, and system information to help with debugging, monitoring, and maintenance.

Logging is an essential part of software development because it provides visibility into how an application behaves during execution. It helps developers identify issues, track user actions, and monitor system performance. Logs can be written to the console, files, databases, or external logging systems. In modern C# applications, logging is often handled using built-in frameworks or libraries like ILogger in ASP.NET Core.

When is Logging Needed?

Use logging when:

• Debugging application issues
• Tracking application flow and user actions
• Monitoring system performance
• Capturing exceptions and errors
• Auditing important operations

How to Implement Logging in C#?

Simple Console Logging

using System;

class Program
{
    static void Main()
    {
        Console.WriteLine("Application started");

        try
        {
            int result = 10 / 0;
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error: " + ex.Message);
        }

        Console.WriteLine("Application ended");
    }
}

File Logging Example

using System;
using System.IO;

class Logger
{
    public static void Log(string message)
    {
        File.AppendAllText("log.txt", $"{DateTime.Now}: {message}\n");
    }
}

class Program
{
    static void Main()
    {
        Logger.Log("Application started");

        try
        {
            int result = 10 / 0;
        }
        catch (Exception ex)
        {
            Logger.Log("Error: " + ex.Message);
        }

        Logger.Log("Application ended");
    }
}

Structured Logging Concept (Example Format)

using System;

class Program
{
    static void Log(string level, string message)
    {
        Console.WriteLine($"[{level}] {DateTime.Now} - {message}");
    }

    static void Main()
    {
        Log("INFO", "Application started");
        Log("ERROR", "Something went wrong");
        Log("INFO", "Application ended");
    }
}

Logging Approaches Comparison

Advantages and Disadvantages

Similar and Alternative Options

Common Mistakes

• Logging too much unnecessary information
• Not logging exceptions properly with stack traces
• Storing sensitive data in logs (passwords, tokens)
• Ignoring log levels (Info, Warning, Error)
• Not rotating or managing log file size
• Relying only on console logs in production