Need .NET code to execute only when in debug configuration

I had this same problem and the solution I went with is using:

if (System.Diagnostics.Debugger.IsAttached)
{
    // Code here
}

This means that technically in production you can attach a debugger and get that piece of code to run.


Solutions

You can use one of the following—

1: Conditional attribute

The Conditional attribute indicates to compilers that a method call or attribute should be ignored unless a specified conditional compilation symbol is defined.

Code example:

[Conditional("DEBUG")]
static void Method() { }

1b: Conditional attribute on local function (C# 9)

Since C# 9, you may use attribute on a local function.

Code example:

static void Main(string[] args)
{
    [Conditional("DEBUG")]
    static void Method() { }

    Method();
}

2: #if preprocessor directive

When the C# compiler encounters an #if preprocessor directive, followed eventually by an #endif directive, it compiles the code between the directives only if the specified symbol is defined. Unlike C and C++, you cannot assign a numeric value to a symbol. The #if statement in C# is Boolean and only tests whether the symbol has been defined or not.

Code example:

#if DEBUG
    static int testCounter = 0;
#endif

3: Debug.Write methods

Debug.Write (and Debug.WriteLine) writes information about the debug to the trace listeners in the Listeners collection.

See also Debug.WriteIf and Debug.WriteLineIf.

Code example:

Debug.Write("Something to write in Output window.");

Notes

Beware of using #if directive since it can produce unintended situations in non-Debug (e.g. Release) build. For example, see:

    string sth = null;
#if DEBUG
    sth = "oh, hi!";
#endif
    Console.WriteLine(sth);

In this case, non-Debug build will print a blank message. But, this potentially may raise NullReferenceException in a different case.

Read more

  • Eric Lippert. What's the difference between conditional compilation and the conditional attribute?
  • C# Programmer's Reference: Conditional Methods Tutorial (archive.org mirror)
  • Bill Wagner. Effective C#: 50 Specific Ways to Improve Your C# (book), chapter: Use Conditional Attributes Instead of #if
  • John Robbins. Assertions and Tracing in .NET (archive.org mirror)
  • Sam Allen. Dot Not Perls:
    • C# Conditional Attribute
    • C# Debug.Write

See also

There is also a tool, DebugView, which allow to capture debug information from external applications.


yes, wrap the code in 

#if DEBUG
// do debug only stuff 
#else
// do non DEBUG stuff
#endif

Google for "C# compilation symbols"

Visual Studio automatically defines DEBUG when you are in the debug configuration. You can define any symbols you want (look at your project's properties, the build tab). Beware that abusing preprocessor directives is a bad idea, it can lead to code that is very difficult to read/maintain.

Tags:

C#

.Net

Vb.Net

Visual Studio

Debugging

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