[C#/.NET]C#/.NET应用程序编程开发中如何实现生成指定范围内的随机小数(浮点数)呢？

2 个回答

• 0

  创建一个生成随机小数的静态扩展方法，如下：

  public static decimal NextDecimal(this Random rnd, decimal from, decimal to)
  {
      byte fromScale = new System.Data.SqlTypes.SqlDecimal(from).Scale;
      byte toScale = new System.Data.SqlTypes.SqlDecimal(to).Scale;
  
      byte scale = (byte)(fromScale + toScale);
      if (scale > 28)
          scale = 28;
  
      decimal r = new decimal(rnd.Next(), rnd.Next(), rnd.Next(), false, scale);
      if (Math.Sign(from) == Math.Sign(to) || from == 0 || to == 0)
          return decimal.Remainder(r, to - from) + from;
  
      bool getFromNegativeRange = (double)from + rnd.NextDouble() * ((double)to - (double)from) < 0;
      return getFromNegativeRange ? decimal.Remainder(r, -from) + from : decimal.Remainder(r, to);
  }
  

  调用示例：

  var rnd = new Random();
  var result = rnd.NextDecimal(1.0M, 9999.0M);
  

  输出结果：9863.58

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  Rector

  2021-01-13 回答
• 0

  另外一个生成随机小数的静态扩展方法，如下：

      public static class RandomExtension
      {
          public static decimal NextDecimal1(this Random rnd, decimal from, decimal to)
          {
              var fromScale = new System.Data.SqlTypes.SqlDecimal(from).Scale;
              var toScale = new System.Data.SqlTypes.SqlDecimal(to).Scale;
  
              var scale = (byte)(fromScale + toScale);
              if (scale > 28)
                  scale = 28;
  
              var r = new decimal(rnd.Next(), rnd.Next(), rnd.Next(), false, scale);
              if (Math.Sign(from) == Math.Sign(to) || from == 0 || to == 0)
                  return decimal.Remainder(r, to - from) + from;
  
              var getFromNegativeRange = (double)from + rnd.NextDouble() * ((double)to - (double)from) < 0;
              return getFromNegativeRange ? decimal.Remainder(r, -from) + from : decimal.Remainder(r, to);
          }
  
          public static int NextInt32(this Random rng)
          {
              var firstBits = rng.Next(0, 1 << 4) << 28;
              var lastBits = rng.Next(0, 1 << 28);
              return firstBits | lastBits;
          }
  
  
          public static decimal NextDecimalSample(this Random random)
          {
              var sample = 1m;
              while (sample >= 1)
              {
                  var a = random.NextInt32();
                  var b = random.NextInt32();
                  var c = random.Next(542101087);
                  sample = new decimal(a, b, c, false, 28);
              }
              return sample;
          }
  
          public static decimal NextDecimal(this Random random)
          {
              return NextDecimal(random, decimal.MaxValue);
          }
  
          public static decimal NextDecimal(this Random random, decimal maxValue)
          {
              return NextDecimal(random, decimal.Zero, maxValue);
          }
  
          public static decimal NextDecimal(this Random random, decimal minValue, decimal maxValue, int places = 2)
          {
              var nextDecimalSample = NextDecimalSample(random);
              return decimal.Round(maxValue * nextDecimalSample + minValue * (1 - nextDecimalSample), places);
          }
      }
  

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  Rector

  2021-01-13 回答