如何清除System.Random种子？

Question

我正在使用System.Random函数为随机数创建/生成种子,然后使用Next()来跟踪数字,但很像c ++,"rng"每次都会得到相同的随机数结果.但是在c ++中通过清除c ++中的种子来解决这个问题,所以我想知道c#中是否也可以这样做？

Answer 1

您很可能Random每次都使用新的实例.您不应该new Random(seed_here)重复实例化.

Random r = new Random(); //Do this once - keep it as a (static if needed) class field 

for (int i = 0; i < 10; i++) {
     Console.WriteLine($"{r.Next()}");
}

更新

这是一个更复杂的例子:

class MyClass
{
    //You should use a better seed, 1234 is here just for the example
    Random r1 = new Random(1234); // You may even make it `static readonly`

    public void BadMethod()
    {
        // new Random everytime we call the method = bad (in most cases)
        Random r2 = new Random(1234); 

        for (int i = 0; i < 3; i++)
        {
            Console.WriteLine($"{i + 1}. {r2.Next()}");
        }
    }

    public void GoodMethod()
    {

        for (int i = 0; i < 3; i++)
        {
            Console.WriteLine($"{i+1}. {r1.Next()}");
        }
    }
}
class Program
{
    static void Main(string[] args)
    {
        var m = new MyClass();

        m.BadMethod();
        m.BadMethod();
        m.GoodMethod();
        m.GoodMethod();

    }
}

产量

1. 857019877
2. 1923929452
3. 685483091    
1. 857019877  <--- Repeats
2. 1923929452
3. 685483091
1. 857019877
2. 1923929452
3. 685483091
1. 2033103372 <--- Phew! It's a new number
2. 728933312
3. 2037485757