Question

我想用try-catch来检查

中除以0

((double)o.Close - (double)subList.Skip(idx - t + 1).First().Close) / 
 (double)subList.Skip(idx - t + 1).First().Close

...但我不知道在哪里添加try-catch。我尝试添加包括整个var newList =，但不允许，因为变量newList以后不再存在。那么添加try-catch的正确位置在哪里？

var newList = data.GroupBy(o => o.Date).Where(o => o.Key <= Beginday).OrderByDescending(o => o.Key).Take(Y).SelectMany(o => o).GroupBy(x => new { x.Symbol })
                .Select
                (
                    x =>
                    {
                        var subList = x.OrderBy(y => y.Date).ToList();
                        return subList.Select((y, idx) =>
                        {
                            return new
                            {
                                Symbol = y.Symbol,
                                Close = y.Close,
                                Date = y.Date,
                                Vol = (idx < t - 1) ? 0 : new DescriptiveStatistics(subList.Skip(idx - t + 1).Take(t)
                                .Select(o =>
                                ((double)o.Close - (double)subList.Skip(idx - t + 1).First().Close) / (double)subList.Skip(idx - t + 1).First().Close).ToList()).StandardDeviation,                              
                        };
                        });
                    }
                )
                .SelectMany(x => x)
                .ToList();

Answer 1

取决于你在catch中要执行的操作 - 如果你希望newList具有有效值，即使除数为0，那么你应该将0检查集成到主代码流中而不是使用特殊流量。

但是，要直接回答您的问题，首先明确将newList声明为默认值，然后在try / catch块中重新分配（将您编写的全部代码放在try中，并使用显式尝试前的默认声明）。然后当您需要稍后使用时，将存在newList。

Answer 2

如果你想抓住一切，那么

        try
          {
            var newList = data.GroupBy(o => o.Date).Where(o => o.Key <=                      Beginday).OrderByDescending(o => o.Key).Take(Y).SelectMany(o => o).GroupBy(x => new { x.Symbol })
            .Select
            (
                x =>
                {
                    var subList = x.OrderBy(y => y.Date).ToList();
                    return subList.Select((y, idx) =>
                    {
                        return new
                        {
                            Symbol = y.Symbol,
                            Close = y.Close,
                            Date = y.Date,
                            Vol = (idx < t - 1) ? 0 : new DescriptiveStatistics(subList.Skip(idx - t + 1).Take(t)
                            .Select(o =>
                            ((double)o.Close - (double)subList.Skip(idx - t + 1).First().Close) / (double)subList.Skip(idx - t + 1).First().Close).ToList()).StandardDeviation,                              
                    };
                    });
                }
            )
            .SelectMany(x => x)
            .ToList();    

            }

     catch(Exception ex)
     {
     //your error
      }

Answer 3

你当然可以这样做：

var newList = new[]
{
    new { Symbol = "", Close = 0.0, Date = DateTime.Now, Vol = 0 }
}.Take(0).ToList();

try
{
    var newList = data.GroupBy(o => o.Date).Where(o => o.Key <= Beginday).OrderByDescending(o => o.Key).Take(Y).SelectMany(o => o).GroupBy(x => new { x.Symbol })
        .Select
        (
            x =>
            {
                var subList = x.OrderBy(y => y.Date).ToList();
                return subList.Select((y, idx) =>
                {
                    return new
                    {
                        Symbol = y.Symbol,
                        Close = y.Close,
                        Date = y.Date,
                        Vol = (idx < t - 1) ? 0 : new DescriptiveStatistics(subList.Skip(idx - t + 1).Take(t)
                        .Select(o =>
                        ((double)o.Close - (double)subList.Skip(idx - t + 1).First().Close) / (double)subList.Skip(idx - t + 1).First().Close).ToList()).StandardDeviation,                              
                };
                });
            }
        )
        .SelectMany(x => x)
        .ToList();    
}
catch (Exception ex)
{
}

只要两个匿名类型中的名称和类型相同，那么这样就可以了。

添加try-catch C＃的适当位置

3 个答案: