c# - 将 List<Guid> 转换为 List<Guid? >

Question

将 List 转换为 List

以下不编译:

public List<Guid?> foo()
{
    List<Guid> guids = getGuidsList();
    return guids; 
}

Answer 1

这个问题似乎改变了几次，所以我会用两种方式展示转换:

转换 List<Guid?>至 List<Guid> :

var guids = nullableGuids.OfType<Guid>().ToList();
// note that OfType() implicitly filters out the null values,
// a Cast() would throw a NullReferenceException if there are any null values

转换 List<Guid>至 List<Guid?> :

var nullableGuids = guids.Cast<Guid?>().ToList();