如何在LINQ语句中将int转换为double

Question

我有这行代码:

IEnumerable<double> katlar = ilanlarQuery.ToList()
                                         .Select(r => r.BulunduguKat.Value)
                                         .OrderBy(f => f);

我得到错误因为BulunduguKat.Value是int,但是katlar是双倍的.如何BulunduguKat.Value在此声明中转换为double？谢谢.

Answer 1

最直接的方式:只需转换为double.通过这样做,你告诉TResult这个Select操作的类型是double- 使这个IEnumerable<double>

IEnumerable<double> katlar = ilanlarQuery.Select(r => (double)r.BulunduguKat.Value)
                                         .OrderBy(f => f);

由于int可以隐式转换为double,因此也可以使用:

IEnumerable<double> katlar  = ilanlarQuery.Select<YourType,double>(i => i.BulunduguKat.Value)
                                          .OrderBy(f => f)();

此外,如您所见,您可以删除.ToList()之前

如果确实BulunduguKat是Nullable<int>蒂姆建议的那么你应该决定:

//If you don't want them in the result collection:
var katlar =  ilanlarQuery.Where(r => r.BulunduguKat.HasValue)
                          .Select(r => (double)r.BulunduguKat.Value)
                          .OrderBy(f => f)

//If you want them with some default value:
var katlar =  ilanlarQuery.Select(r => (double)(r.BulunduguKat.HasValue ? r.BulunduguKat.Value : 0))
                          .OrderBy(f => f);