C#中预处理指令的实现

#define DEBUG_MODE

public class Program
{
    public static void Main()
    {
#if DEBUG_MODE
        Console.WriteLine("Debug mode is enabled.");
#endif
    }
}
//会输出： Debug mode is enabled.

public class PlatformSpecificCode
{
    public static void Main()
    {
#if UNITY_ANDROID
        //如果你正在为Android平台进行构建，并且使用Unity引擎
        Console.WriteLine("Running on Android with Unity.");
#elif UNITY_IOS
        //为iOS平台构建时，可以启用iOS专用代码
        Console.WriteLine("Running on iOS with Unity.");
#elif UNITY_STANDALONE
        //此符号可用于PC、Mac等独立平台
        Console.WriteLine("Running on a standalone platform with Unity.");
#else
        Console.WriteLine("Running on an unsupported platform.");
#endif

public class Program
{
    #region Helper Methods

    private void HelperMethod1()
    {
        // Method implementation
    }

    private void HelperMethod2()
    {
        // Method implementation
    }

    #endregion
}

#warning This is a warning message
#error This is an error message

#line 200 "NewFileName"