如何在C#中使用#undef指令？
#undef指令允许您取消定义符号。以下是语法-
#undef SYMBOL
例如，
#undef One
与#if指令一起使用时，其计算结果为false。让我们看一个例子-
示例
#define One
#undef Two
using System;
namespace Demo {
class Program {
static void Main(string[] args) {
#if (One && TWO)
Console.WriteLine("Both are defined");
#elif (ONE && !TWO)
Console.WriteLine("ONE is defined and TWO is undefined");
#elif (!ONE && TWO)
Console.WriteLine("ONE is defined and TWO is undefined");
#else
Console.WriteLine("Both are undefined");
#endif
}
}
}输出结果
Both are undefined