C #ifdef

In C#, the #ifdef directive is not available like it is in C or C++. C# does not provide a preprocessor for conditional compilation based on preprocessor directives.

In C and C++, #ifdef is used to conditionally compile sections of code based on the defined or undefined state of a preprocessor symbol. For example:

#define DEBUG

#ifdef DEBUG
    Console.WriteLine("Debug mode is enabled");
#else
    Console.WriteLine("Debug mode is disabled");
#endif

However, in C#, conditional compilation is achieved using conditional attributes such as Conditional and ConditionalAttribute. These attributes allow methods or entire classes to be conditionally compiled based on the presence or absence of specific symbols.

Here’s an example:

#define DEBUG

using System.Diagnostics;

public class Program
{
    [Conditional("DEBUG")]
    public static void DebugMethod()
    {
        Console.WriteLine("Debug mode is enabled");
    }

    public static void Main(string[] args)
    {
        DebugMethod();
    }
}

In this example, the [Conditional("DEBUG")] attribute specifies that the DebugMethod should only be included in the compiled code if the symbol DEBUG is defined. If DEBUG is not defined, the method call will be completely omitted during compilation.

It’s important to note that the Conditional attribute does not provide the same level of flexibility as the preprocessor directives in C or C++. It can only be used to conditionally include or exclude entire methods or classes, and not individual code blocks within a method.