没有从列表中得到任何结果 [英] not getting any result from the list

问题描述

大家好，

我列出了一些项目，例如"codeproject"，"stackoverflow"，"msdn".我使用Where过滤列表，并分配给以下变量，

Hello All,

I have list with few items such as "codeproject", "stackoverflow", "msdn". I filter the list using Where and assign to a variable as below,

var output= list.Where(i=>i.Length>5);

但输出中没有任何内容.

我想不通，请帮助我.

but there is nothing in the output.

I cannt figured out, please help me.

推荐答案

我确定它在那里；您只是由于某种原因而看不到它.这将显示一些输出:

I''m sure it''s there; you only failed to see it by some reason. This will show some output:

string[]
using System.Linq;

//...

list = new string[] {
    "CodeProject", "StackOverflow", "MSDN", "Google", "Bing", "Yahoo", };
var output = list.Where(i => i.Length > 5);
foreach (var item in output)
    System.Console.WriteLine(item);

如预期的那样，在输出上您将看到:

As expected, on output you will see:

CodeProject
StackOverflow
Google

如果将list设为类型为System.Collection.Generic.List<string>的列表，则可以看到相同的内容.尝试什么? :-)

—SA

You can see the same if you make list a list of the type System.Collection.Generic.List<string>. What to try? :-)

—SA

在此阶段，输出没有任何内容，因为您尚未实际计算该表达式.您要做的只是创建一个查询表达式.在尝试执行First或Take或Count等操作之前，不会得到任何输出.

There is nothing in the output at this stage because you haven''t actually evaluated the expression. All you''ve done is create a query expression. You don''t get any output from it until you attempt to do something like a First or Take or Count, etc...

由于延迟执行 [在何处选择 [

because of Deferred Execution[^] and Where and Select[^]

Hope it helps :)

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