在C＃中是否有类似“超出范围”的东西？还有一些相关的问题

I am a C#-Newbie.

我是C# - 新手。

I have a function that is supposed to return all values from a List, that have the matching time-stamp:

我有一个函数应该返回List中的所有值,它们具有匹配的时间戳:

static public PointCloud getPointsByTime (float time)
{
    PointCloud returnList = new List<PointData> ();

    for (int i = 0; i < _pointCloud.Count; i++) {
        if (_pointCloud [i].time == time) {
            returnList.Add (_pointCloud [i]);
        }
    }

    return returnList;
}

Where

public class PointData
{
    public float time;
    // and some other members
}

and

// let's call a list of PointData-objects a PointCloud
using PointCloud = System.Collections.Generic.List<PointData>;

Does my function do what I want it to do? Or do I have to create a new PointData-object? Am I able to use my returned PointCloud or will it be out of scope and deleted?

我的功能是否符合我的要求?或者我是否必须创建一个新的PointData对象?我可以使用我返回的PointCloud还是超出范围并删除?

This may be not the best example to explain so feel free to link me to something better. I think you get what my basic quastions are.

这可能不是解释的最好例子,所以请随意将我链接到更好的东西。我想你得到了我的基本规则。

2 个解决方案

#1

Your code is correct. You can use your function like so:

你的代码是正确的。您可以像这样使用您的函数:

var someTime = 0.0f;
var pointsAtTime = getPointsByTime(someTime);
DoSomethingWith(pointsAtTime);

The return value from the function remains in scope if you assign it to some local variable (e.g. pointsAtTime here).

如果将其分配给某个局部变量(例如,此处为pointsAtTime),则函数的返回值仍在范围内。

EDIT: As Peter Schneider correctly notes in the comments, you need to be aware that this function creates a new list with references to the matching points, and does not create new points. This might or might not be what you want.

编辑:正如Peter Schneider在评论中正确指出的那样,您需要知道此函数会创建一个新列表,其中包含对匹配点的引用,并且不会创建新点。这可能是也可能不是你想要的。

However, if you're new to C#, here are some things you might want to keep in mind:

但是,如果您是C#的新手,请注意以下几点:

Methods in C# are conventionally named in TitleCase, e.g. GetPointsByTime and not getPointsByTime.

C#中的方法通常在TitleCase中命名,例如, GetPointsByTime而不是getPointsByTime。

Assigning names to generic types like using PointCloud = List<PointData>, while technically allowed, is not very idiomatic and might confuse other readers of your code. If you think a list of PointData is special enough to have its own type, create a type for it (either by inheriting from List<PointData> or, preferably, using a IList<PointData> as a member in a new PointCloud class). Or just use using System.Collections.Generic and use List<PointData> throughout your code, which is what most people would do.

将名称分配给泛型类型,例如使用PointCloud = List ,虽然技术上允许,但不是非常惯用,可能会使代码的其他读者感到困惑。如果您认为PointData列表特别足以拥有自己的类型,请为其创建一个类型(通过继承List ,或者最好使用IList 作为新PointCloud类中的成员)。或者只是使用System.Collections.Generic并在整个代码中使用List ,这是大多数人会做的。

Comparing floating-point numbers for equality is sometimes discouraged as this might fail in some cases due to representation errors; if the time is truly a continuous value, you might want to look for points in a specific time period (e.g. points who fall within some range around your desired time). You don't really have to worry about this for now, though.

有时不鼓励比较浮点数是否相等,因为在某些情况下,由于表示错误,这可能会失败;如果时间确实是连续值,您可能希望在特定时间段内查找点数(例如,在您所需时间内的某个范围内的点数)。不过,你现在不必担心这个问题。

#2

As @Patrick suggested inheriting for List seems more reasonable, but I would go further and I would just use a List so you don't create an unnecessary class if it is not going to add anything extra.

正如@Patrick建议继承List似乎更合理,但我会更进一步,我只会使用一个List,所以你不创建一个不必要的类,如果它不会添加额外的东西。

Also I suggest you to have a look to LINQ which makes the code more readable and is a very powerful feature that you would like to master as soon as possible. :)

另外,我建议你看看LINQ,它使代码更具可读性,是一个非常强大的功能,你想尽快掌握。 :)

Your method could look then like this:

你的方法看起来像这样:

_pointCloud.Where(p => p.time == time).ToList();

Also try to get familiar with properties:

还尝试熟悉属性:

public class PointData
{
      public float Time { get; set; }
}

And you may want to follow the more standard C# coding style (although this is completely personal) of using PascalCase for public members instead of camelCase.

并且您可能希望遵循更标准的C#编码风格(尽管这完全是个人的)将PascalCase用于公共成员而不是camelCase。

#1