在LINQ中使用挂起的请求时，信息保存在内存中 [英] Information saved in memory when using pending request in LINQ

问题描述

我正在学习LINQ，并且我想使用待处理的请求，但是我遇到了这个问题

I learning LINQ, and i want to use pending request, but i have this problem

            List<string> _strs = new List<string> { "1", "2", "1", "1", "0" };
            var selind = _strs.Select((name, ind) => new { indexname = name, index = ind }).Where(o => o.indexname == "1");
            string sind = "";
            foreach (var item in selind)
                sind += item.index.ToString() + " ";
            //i get 0 2 3 
            _strs.Add("2");
            _strs.Add("1");
            sind = "";
            foreach (var item in selind)
                sind += item.index.ToString() + " ";
            //Good, i get 0 2 3 6
            _strs = new List<string>() { "1" };
            sind = "";
            foreach (var item in selind)
                sind += item.index.ToString() + " ";
            //Why i get again 0 2 3 6

好的，我理解为什么，但是我很想知道两件事:

Ok i understand why, but I wolud like to know two things:

• 我应该如何清除内存?

• How should i clear memory?

selind = null; 还是可以告诉我更多更好的方法?

selind = null; Or you can tell me more nice way?

要在完全重建_strs后使用selind，我会找到两种方法

For work with selind after total rebuild of _strs i find two way

        _strs.Clear();
        _strs.Add();

或再次致电

selind = _strs.Select((name, ind) => new { indexname = name, index = ind }).Where(o => o.indexname == "1");

您能以另一种方式建议我吗?

Can you advice me another way?

提前谢谢！

推荐答案

您的查询:

_strs.Select((name, ind) => new { indexname = name, index = ind }).Where(o => o.indexname == "1");

绑定到内存中的特定列表引用(无论当时的_strs是什么)，而不是特定的变量名称.它们不是同一件事.当您这样做时:

Is tied to a particular list reference in memory (whatever _strs is at that time), not to a particular variable name. They are not the same thing. When you do this:

_strs = new List<string>() { "1" };

您不会清除_strs最初指向的内存引用.取而代之的是，让该变量名指向新的内存位置.而_strs.Clear()确实清除了原始列表.

You're not clearing the memory reference of where _strs originally pointed. You are instead having that variable name point to a new memory location. Whereas _strs.Clear() does clear the original list.

针对您的问题的最佳解决方案是将LINQ查询包装在接受列表的函数中，因此您可以在新列表上再次调用它而无需再次键入.另外，根据您的使用情况，在需要再次启动时只需调用.Clear().

The best solution for your problem is to wrap the LINQ query in a function that accepts a list, so you can call it again on new lists without typing it again. Alternatively, depending on your use case, just call .Clear() when you need to start again.

(如果不清楚，_strs = null对_strs所指向的列表不执行任何操作，只会使该特定变量名称无效)

(in case this wasn't clear, _strs = null does nothing to the list that _strs used to point to, it just makes that particular variable name invalid)

这篇关于在LINQ中使用挂起的请求时，信息保存在内存中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！