Debug Class vs Debugger Class in C#

The Debug class and Debugger class in C# are both part of the System.Diagnostics namespace but serve different purposes. The Debug class provides methods for conditional debugging output, while the Debugger class enables communication and interaction with debuggers attached to your application.

Debug Class

The Debug class is a static class that provides conditional compilation methods for debugging. It outputs information only when the DEBUG symbol is defined during compilation −

public static class Debug

Properties of Debug Class

Example

using System;
using System.Diagnostics;

class Program {
   public static void Main() {
      Debug.WriteLine("Debug output - this appears in debug mode");
      Debug.WriteLineIf(true, "Conditional debug output");
      
      Debug.IndentLevel = 1;
      Debug.WriteLine("Indented debug message");
      
      Debug.Assert(5 > 3, "This assertion passes");
      Debug.Assert(2 > 5, "This assertion would fail in debug mode");
      
      Console.WriteLine("Program execution completed");
   }
}

The output of the above code (in debug mode) is −

Program execution completed

Debugger Class

The Debugger class is a sealed class that provides communication with debuggers. It cannot be inherited and offers methods to interact with attached debuggers −

public sealed class Debugger

Properties of Debugger Class

Example

using System;
using System.Diagnostics;

class Program {
   public static void Main() {
      if (Debugger.IsAttached) {
         Console.WriteLine("Debugger is attached");
         Debugger.Break(); // Triggers a breakpoint
      } else {
         Console.WriteLine("No debugger attached");
      }
      
      Console.WriteLine("Checking if debugger is present: " + Debugger.IsAttached);
      Console.WriteLine("Program continues execution");
   }
}

The output of the above code is −

No debugger attached
Checking if debugger is present: False
Program continues execution

Key Differences

Conclusion

The Debug class is used for conditional debugging output and works only in debug builds, while the Debugger class provides runtime interaction with attached debuggers. Use Debug class for logging debug information and Debugger class when you need to programmatically control debugger behavior.