c# - 类设计质量

Question

我编写的这个类是否足以包含在代码/项目中(我指的是专业人士的做法)？还是我错过了重要的事情？我不知道如何使用构造函数等，所以我没有使用它们(我只是 C# 的初学者)，但如果需要请评论。

using System;
using System.Collections.Generic;
using System.Text;

namespace RandBit
{
    /// <summary>
    /// By: Author
    /// Version 0.0.1
    /// Pseudo-Random 16-Bit (Max) Generator.
    /// </summary>
    public class RandomBit
    {
        /// <param name="input">The Bit-size(int)</param>
        /// <returns>Random Bit of Bit-size(string)</returns>
        public static string Generate(int input)
        {
            int bitSize = 0;
            Random choice = new Random();
            if (input == 0 || input > 16)
            {
                bitSize = 0;
            }
            else if (input == 1)
            {
                bitSize = 1;
            }
            else
            {
                int randomChoice = choice.Next(0, (1 << input));
                bitSize = randomChoice;
            }
            string binary = Convert.ToString(bitSize, 2);
            binary = binary.PadLeft(input, '0');
            return binary;
        }
    }
}

谢谢。

Answer 1

您似乎错误地使用了 Random。我建议从 Jon Skeet's article on the subject 开始.相关引用:

If you start off an instance of Random with the same initial state (which can be provided via a seed) and make the same sequence of method calls on it, you'll get the same results.

So what was wrong in our example code? We were using a new instance of Random on each iteration of the loop. The parameterless constructor for Random takes the current date and time as the seed - and you can generally execute a fair amount of code before the internal timer works out that the current date and time has changed. Therefore we're using the same seed repeatedly - and getting the same results repeatedly.

换句话说，由于您在每次调用时都创建了一个新的 Random 实例，因此您大大增加了返回值不像您期望的那样“随机”的可能性。

还值得一提的是，还有potentially better .Net BCL 中已有 PRNG 类。这是编写类似代码的另一种方法。

private static readonly RNGCryptoServiceProvider _crypto = new RNGCryptoServiceProvider();

public static long Generate(){
    // use whatever size you want here; bigger has a better chance of 
    // being unique in a given scope
    byte[] bytes = new byte[8];

    // puts random bytes into the array
    _crypto.GetBytes( bytes );

    // do something (your choice) with the value...
    return BitConverter.ToInt64( bytes, 0 );
}