循環故障時，隨機積分器僅在第一次工作

Question

此代碼應該生成一個隨機數，然后查看該位置是否已被占用或可用，它第一次工作正常，但是當它的機器人第二輪時，它只是垃圾郵件錯誤：您已經放置在這里，再試一次. 我正在為學校制作一個連續 3 個機器人，但我被卡住了。

    static int EasyMode(int plats1, int plats2, int plats3, int plats4, int plats5, int plats6, 
    int plats7, int plats8, int plats9) {
    DateTime dt = DateTime.Now;
    int random = dt.Millisecond;
    random = dt.Millisecond;
    random = (random / 100);
    bool finished = false;
    while (finished == false) {
        random = dt.Millisecond;
        random = (random / 100);
        if (random == 0) {
            random = dt.Millisecond;
            random = (random / 100);
        }
        else if (random == 10) {
            random = dt.Millisecond;
            random = (random / 100);
        }
        else {
            switch (random) {
                case 1:
                    if (plats1 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats1 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 1;
                    }
                case 2:
                    if (plats2 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats2 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 2;
                    }
                case 3:
                    if (plats3 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats3 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 3;
                    }
                case 4:
                    if (plats4 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats4 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 4;
                    }
                case 5:
                    if (plats5 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats5 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 5;
                    }
                case 6:
                    if (plats6 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats6 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 6;
                    }
                case 7:
                    if (plats7 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats7 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 7;
                    }
                case 8:
                    if (plats8 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats8 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 8;
                    }
                case 9:
                    if (plats9 == 1) {
                        Console.WriteLine("Error: You've already placed on here, try again.");
                        continue;
                    }
                    else if (plats9 == 2) {
                        Console.WriteLine("Error: This spot is taken by the bot");
                        continue;
                    }
                    else {
                        Console.WriteLine("Success");
                        finished = true;
                        return 9;
                    }
            }
            continue;
        }
        continue;
    }
    return 69;
}

（我需要更多細節）

Answer 1

如果你需要隨機值，你應該使用Random class。 像這樣：

var rnd = new Random();
int random = rnd.Next(1, 10); // assuming 1 is minimum and 9 is maximum, 
// upper boundary is exclusive 
bool finished = false;
while (finished == false) {
    // generate value here the same way if needed

Answer 2

你的隨機數總是一樣的。 變量dt不會像您預期的那樣使用DateTime.Now的值進行更新。 該值設置一次（當您分配它時）到當前時間。

為了保持當前機制的完整性，您需要繼續查詢DateTime.Now.Millisecond （而不是dt ）

while(!finished)
{
     int random = DateTime.Now.Millisecond / 100;
     // do stuff with random value
     // if zero or ten, continue loop go get new value
     if (random == 0 || random == 10) {
         continue;
     } else {
         // etc 
     } 
}

但請注意，在這樣的循環中， DateTime.Millisecond並不是最好的選擇。 由於其精度和此循環的性質，許多連續的迭代可能最終得到相同的值。 加上它本身並不是最好的隨機數生成器。

您真正應該做的是使用專門為此目的的框架 class - Random - 獲取 0 到 99 之間的值

var rand = new Random(); // outside of loop
while(!finished)
{
     var random = rand.Next(0, 100);
     // do stuff with random value
     // if zero or ten, continue loop go get new value
     if (random == 0 || random == 10) {
         continue;
     } else {
         // etc 
     } 
}

另請注意，您似乎確實想要介於 0-10（或者更確切地說，包括 1-9）之間的數字，在這種情況下，您可以使用以下任何一種：

使用Random並正確設置邊界：

int random = rand.Next(1, 10); // 1-9

使用Millisecond模 10：

int random = DateTime.Now.Millisecond % 10; // 0-9,  still need to test its not zero

使用Millisecond模 9：

int random = (DateTime.Now.Millisecond % 9) + 1; // 1-9