如何从主要大字符串中获取子字符串？ [英] How to Get sub string from main big string ?

问题描述

您好，

我想从主字符串中获取子字符串，如下所示。

我的主要字符串是

< iframe width =640height =360src =https://www.youtube.com/embed/KVlXccl-XBAframeborder =0allowfullscreen>< / iframe> 

我想从这里得到这个唯一的网址就像

https://www.youtube.com/embed/KVlXccl-XBA



所以请让我知道如何从我的主字符串中找到这个子字符串。

解决方案

您可以使用正则表达式来实现此目的。试试这个

正则表达式正则表达式= 新正则表达式（  src = \（。*）\）; 

这里有一个解决方案，你不使用正则表达式：

  string  mainString =  < iframe width = \ 640 \height = \360 \src = \https://www.youtube.com/embed/KVlXccl-XBA\frameborder = \0 \allowfullscreen>< /的iframe>中; 
 
  int  start = mainString.IndexOf（  src = \）+  5 ; 
  int  count = mainString.Length  -  mainString.IndexOf（  \，start） -   2 ; 
 
  string  subString = mainString.Substring（start，count）; 

< blockquote>除了正则表达式解决方案，如果您加载的文本是html，您可以使用敏捷包来解析它



https://htmlagilitypack.codeplex.com/ [ ^ ]



如果html是有效的xml，你甚至可以使用XmlDocument来解析它。

Hello,
I want to get sub string from main string like follows .
My main string is

<iframe width="640" height="360" src="https://www.youtube.com/embed/KVlXccl-XBA" frameborder="0" allowfullscreen></iframe>

I want to get only url from this this like
https://www.youtube.com/embed/KVlXccl-XBA

So please let me know how to find this sub string from my main string.

解决方案

You can use Regular Expression for this purpose. Try this

Regex regex = new Regex("src=\"(.*)\"");

Also here is a solution for you that does not use Regex:

string mainString = "<iframe width=\"640\" height=\"360\" src=\"https://www.youtube.com/embed/KVlXccl-XBA\" frameborder=\"0\" allowfullscreen></iframe>";

int start = mainString.IndexOf("src=\"") + 5;
int count = mainString.Length - mainString.IndexOf("\"", start) - 2;

string subString = mainString.Substring(start, count);

In addition to regex solutions, if the text you are loading is html you can use the agility pack to parse it

https://htmlagilitypack.codeplex.com/[^]

If the html is valid xml you could even use XmlDocument to parse it.

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