从URL字符串中提取查询字符串 [英] extract query string from a URL string

问题描述

我正在阅读历史记录，我希望当我遇到Google查询时，我可以提取查询字符串.我不使用请求或httputility，因为我只是解析一个字符串.但是，当我遇到这样的URL时，我的程序无法正确解析它:

I am reading from history, and I want that when i come across a google query, I can extract the query string. I am not using request or httputility since i am simply parsing a string. however, when i come across URLs like this, my program fails to parse it properly:

我想做的是获取q =的索引和&的索引.并使用介于两者之间的单词，但在这种情况下，索引为&会小于q =，这会给我错误.

what i was trying to do is get the index of q= and the index of & and take the words in between but in this case the index of & will be smaller than q= and it will give me errors.

有什么建议吗?

感谢您的回答，一切似乎都很好:) p.s.我不能使用httputility，不是我不想.当我添加对system.web的引用时，不包括httputility！它仅包含在asp.net应用程序中.再次感谢

thanks for your answers, all seem good :) p.s. i couldn't use httputility, not I don't want to. when i add a reference to system.web, httputility isn't included! it's only included in an asp.net application. Thanks again

推荐答案

目前尚不清楚为什么您不想使用HttpUtility.您始终可以添加对 System.Web 的引用并使用它:

It's not clear why you don't want to use HttpUtility. You could always add a reference to System.Web and use it:

var parsedQuery = HttpUtility.ParseQueryString(input);
Console.WriteLine(parsedQuery["q"]);

如果这不是一种选择，那么也许这种方法会有所帮助:

If that's not an option then perhaps this approach will help:

var query = input.Split('&')
                 .Single(s => s.StartsWith("q="))
                 .Substring(2);
Console.WriteLine(query);

它将在& 上拆分并查找以"q =" 开头的单个拆分结果，并采用位置2的子字符串返回之后的所有内容> = 符号.假设只有一个匹配项，在这种情况下似乎是合理的，否则将引发异常.如果不是这种情况，则将 Single 替换为 Where ，在结果中循环并在循环中执行相同的子字符串操作.

It splits on & and looks for the single split result that begins with "q=" and takes the substring at position 2 to return everything after the = sign. The assumption is that there will be a single match, which seems reasonable for this case, otherwise an exception will be thrown. If that's not the case then replace Single with Where, loop over the results and perform the same substring operation in the loop.

编辑:以覆盖此注释可以使用的更新版本:

to cover the scenario mentioned in the comments this updated version can be used:

int index = input.IndexOf('?');
var query = input.Substring(index + 1)
                 .Split('&')
                 .SingleOrDefault(s => s.StartsWith("q="));

if (query != null)
    Console.WriteLine(query.Substring(2));

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