#define MYTEST
#define DEBUG

using System;
using System.Collections.Generic;
using System.Text;

namespace PreprocessorDirectives
{
    class Program
    {
        static void Main( string[] args )
        {
            #if (DEBUG && !MYTEST)
                    Console.WriteLine("DEBUG is defined");
            #elif (!DEBUG && MYTEST)
                    Console.WriteLine("MYTEST is defined");
            #elif (DEBUG && MYTEST)
                        Console.WriteLine( "DEBUG and MYTEST are defined" );
            #else
                    Console.WriteLine("DEBUG and MYTEST are not defined");
            #endif
        }
    }
}

代码是从msdn上copy的，问题是我怎么才能让最后一句Console.WriteLine("DEBUG and MYTEST are not defined");执行呢？我试过把#define MYTEST #define DEBUG这两行注释掉都不行啊



C#中，预编译符不是写上就可以的，你还需要在项目属性里面build，条件编译符号里面定义上你这个MYTEST才行，这个需要两个步骤

http://zhidao.baidu.com/link?url=Yo04iwUE4zzzpHj4KASrP2omISANDN68g_NfjMVrrcJWyLQX_dc1ddi0l5QDR1JdNvcuDtMdJos5iW2U7dmzuK