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[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?

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如题,在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?我们知道,在C#中内置的随机数命名空间System.Random中,可以随机生成指定范围内整数的方法,但没有直接生成随机小数的方法,如果要生成指定范围内的随机小数(浮点数),应该如何实现呢?

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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

    Rector的个人主页

    Rector

    13天前 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);
              }
          }
      
      Rector的个人主页

      Rector

      13天前 回答

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