(C#) 我怎样才能使所有这些 "else if" 语句更简洁，我怎样才能更好地优化我的代码？

Question

好的，我有一大堆 else if 语句，有没有办法将它们压缩成更少的代码行？喜欢为所有这些做一个 if 语句吗？有什么方法可以使我的代码更优化和更易于阅读？

            int x;
            int y;
            int time=0;
            Random rng = new Random();
            int hrand_num = rng.Next(-24000, 24000);
            int vrand_num = rng.Next(-24000, 24000);
            x = hrand_num;
            y = vrand_num;
            


            while (true)
            {
                ConsoleKey key = Console.ReadKey().Key;
                
                 
                if (key == ConsoleKey.UpArrow)
                {


                    y=y+2000;
                   
                }
                else if (key == ConsoleKey.DownArrow)

                {

                   y=y-2000;

                }
                else if (key == ConsoleKey.LeftArrow)
                {
                    x = x-1000;
                }
                else if (key == ConsoleKey.RightArrow)
                {
                    x = x+1000;
                }
                // Circumnavigate Players Position.
                  // North and South
                if (y >= 24001)
                {
                    y = -24000;
                }

                else if (y <= -24001)
                {
                    y = 24000;
                }
                  //West and East
                else if (x >= 24001)
                {
                    x = -24000;
                }
                else if (x <= -24001)
                {
                    x = 24000;
                }

                // Setting Time Zones

                if (x >= -2000 && x <= 0 )
                {
                    time = 0;
                }
                else if (x >=
                    1 && x <= 2000)
                {
                    time = 1;
                }
                else if (x >= 2001 && x <=4000)
                {
                    time = 2;
                }

                else if (x >= 4001 && x <= 6000)
                {
                    time = 3;
                }

                else if (x >= 6001 && x <= 8000)
                {
                    time = 4;
                }

                else if (x >= 8001 && x <= 10000)
                {
                    time = 5;
                }
                else if (x >= 10001 && x <= 12000)
                {
                    time = 6;
                }
                else if (x >= 12001 && x <= 14000)
                {
                    time =  7;
                }
                else if (x >= 14001 && x <= 16000)
                {
                    time =  8;
                }
                else if (x >= 16001 && x <= 18000)
                {
                    time =  9;
                }
                else if (x >= 18001 && x <= 20000)
                {
                    time =  10;
                }
                else if (x >= 20001 && x <= 22000)
                {
                    time =  11;
                }
                else if (x >= 22001 && x <= 24000)
                {
                    time = 12;
                }
                else if (x == -24000 && x <= -22001)
                {
                    time = 13;
                }
                else if (x >= -22000 && x <= -20001 )
                {
                    time = 14;
                }
                else if (x >= -20000 && x <= -18001)
                {
                    time = 15;
                }
                else if (x >= -18000 && x <= -16001)
                {
                    time = 16;
                }
                else if (x >= -16000 && x <= -14001)
                {
                    time =  17;
                }
                else if (x >= -14000 && x <= -12001)
                {
                    time = 18;
                }
                else if (x >= -12000 && x <= -10001)
                {
                    time = 19;
                }
                else if (x >= -10000 && x <= -8001)
                {
                    time =  20;
                }
                else if (x >= -8000 && x <= -6001)
                {
                    time = 21;
                }
                else if (x >= -6000 && x <= -4001)
                {
                    time = 22;
                }
                else if (x >= -4000 && x <= -2001)
                {
                    time = 23;
                }
 
                Console.WriteLine($"X: {x,6} Y: {y,6} Time: {time,3}");
            }   
         ```     

Answer 1

假设您使用的是 C# 8.0，您可以查看 switch 语句和 switch 表达式：https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/switch-expression (additionaly the patterns documentation is also helpful: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/patterns)

所以你可以这样写：

switch (key)
{
  case ConsoleKey.UpArrow:
    y=y+2000;
    break;
  // [...]
}

time = x switch
{
  >= -2000 and <= 0 => 0,
  >= 1 and <= 2000 => 1
  // [...]
};

Answer 2

我建议您利用：

• a switch statement 用于解释方向键
  • 将 switch 语句与 if 循环进行比较，您可以将第一个 case 视为 if 条件，将后面的 case 视为 else if 条件
• Math.Abs( ) and Math.Sign( ) 用于环绕玩家的位置
  • Math.Abs( ) returns 变量的绝对值；例如Math.Abs(x) return 5 x = 5 和 x = -5
  • Math.Sign( ) returns 值的符号；如果值为负数，则returns -1；如果是正数，则 returns 1；如果两者都不是 (0)，则它 returns 0。这有助于我们确定更新值的所需符号。
• a switch expression 用于设置 time
  • 鉴于time的值最终是由x决定的，可以使用switch表达式而不是switch语句来决定它的值。 switch 表达式表示要根据 x 的值确定 time 的值；并将以下每个条件与 x 进行比较（<= -22001 计算为 x <= -22001）。如果条件评估为 true，则提供的值设置为 time 的值（=> 13 然后设置 time = 13）。

可以这样实现：

int x;
int y;
Random rng = new Random();
int hrand_num = rng.Next(-24000, 24000);
int vrand_num = rng.Next(-24000, 24000);
x = hrand_num;
y = vrand_num;

while (true)
{
    switch (Console.ReadKey().Key)
    {
        case ConsoleKey.UpArrow:
            y += 2000;
            break;
        case ConsoleKey.DownArrow:
            y -= 2000;
            break;
        case ConsoleKey.LeftArrow:
            x -= 1000;
            break;
        case ConsoleKey.RightArrow:
            x += 1000;
            break;
    }

    // Circumnavigate Players Position.
    // North and South
    if (Math.Abs(y) > 24000)
    {
        y = -(Math.Sign(y) * 24000);
    }
    //West and East
    else if (Math.Abs(x) > 24000)
    {
        x = -(Math.Sign(x) * 24000);
    }

    // Setting Time Zones
    var time = x switch
    {
        <= -22001   => 13,
        <= -20001   => 14,
        <= -18001   => 15,
        <= -16001   => 16,
        <= -14001   => 17,
        <= -12001   => 18,
        <= -10001   => 19,
        <= -8001    => 20,
        <= -6001    => 21,
        <= -4001    => 22,
        <= -2001    => 23,
        <= 0        => 0,
        <= 2000     => 1,
        <= 4000     => 2,
        <= 6000     => 3,
        <= 8000     => 4,
        <= 10000    => 5,
        <= 12000    => 6,
        <= 14000    => 7,
        <= 16000    => 8,
        <= 18000    => 9,
        <= 20000    => 10,
        <= 22000    => 11,
        <= 24000    => 12,
        _ => 0
    };

    Console.WriteLine($"X: {x,6} Y: {y,6} Time: {time,3}");

我还建议引入一些常量；特别是对于值 24000.

Answer 3

您可以使用以下内容涵盖所有 time 个案例

var time = x <= 24000
    ? x / 2000 + 1;
    : (24000 - x) / 2000 + 13;