#506 – Using Expressions in #if and #elif Directives

You can use more complex expressions in #if and #elif directives, instead of just checking to see whether a single conditional compilation symbol is defined.

In the example below, the #elif directive triggers if the DOGSBARK symbol is defined and then DOGSGROWL symbol is not defined.

#define DOGSBARK
//#define DOGSWAG
//#define DOGSGROWL

using System;
using DogLibrary;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main()
        {
            Dog d = new Dog("Kirby", 12);

#if DOGSWAG
            d.WagTail();
#elif DOGSBARK && !DOGSGROWL
            d.Bark();
#else
            d.BarkAndGrowl();
#endif

        }
    }
}

You can build more complex expressions using parentheses and the && (logical AND) and || (logical OR) operators.

#if (DOGSWAG && DOGSDOTRICKS) || (DOGSDOEVERYTHING)
            d.WagAndFetch();
#endif
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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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